Anycubic Kobra 2 Plus Review

At a glance

Expert’s Rating

Pros

• 320 x 320 x 400mm build volume
• Relatively affordable
• Fast

Cons

• Takes up a lot of space
• Filament reel holder position could be better
• Cloud printing doesn’t work properly

Our Verdict

The Kobra 2 Plus is a good-value 3D printer for those that need a large build volume for big models, and don’t want to wait long for them to be printed. Quality is decent with the right filament, too. Problems with cloud printing and noisy fans took the shine off, though.

Best Prices Today: Anycubic Kobra 2 Plus

Having previously reviewed Anycubic’s Vyper and being impressed with its reliability and overall quality, I was keen to see how far things had progressed with the Kobra 2 series.

Unlike coreXY printers such as the Bambu P1S and Creality K1 , the Kobra 2 printers stick with the traditional “bed-slinger” design. This is where the print surface moves backwards and forwards and the print head moves side to side (and upwards).

The coreXY motion system lends itself to faster printing but manufacturers have figured out how to increase the print speed of bed-slingers. The Kobra 2 Plus, then, claims to be 10X faster than traditional models and can print a 3Dbenchy in 17 minutes.

There are four other models in the range: the Kobra 2 Neo , Kobra 2, Kobra 2 Pro and Kobra 2 Max . The Neo is the budget model which prints at a maximum of 250mm per second, the Kobra 2 at 300mm per second and the other three can – theoretically – go up to 500mm per second.

The main difference between them is build volume. The Kobra 2, Neo and Pro are all 220x220x250mm, the Plus is 320x320x400mm / 15.7×12.6×12.6 inches and the Max can print enormous models up to 420x420x500mm.

This review is focused on the Plus, which costs £449 / $449 .

Features & Design

• Automatic levelling
• 4.3-inch touchscreen
• Direct-drive extruder

If you’re new to 3D printing you might think you need a bigger build volume that you really do. More often than not models are quite small, but then again, it depends on what exactly you want to print.

This type of 3D printer uses standard 1.75mm filament. PLA is the most common type of filament and it’s very easy to glue together using superglue, so it’s possible to print large models by splitting them up into smaller sections and printing them individually.

I asked Anycubic to send the Kobra 2 Plus because I wanted to find out if it had managed to create a bed-slinger that could print as quickly as a coreXY printer at a bigger-than-usual size.

As the build volume increases, the harder it is to print accurately. That’s one reason why the Plus has supporting rods for the gantry and two z-axis motors (and therefore two leadscrews) to keep everything stable.

Jim Martin / Foundry

Like many other 3D printers, the Kobra 2 Plus has a heated bed with a magnetic and therefore removable textured steel plate. Once printing is finished, you simply lift off this plate and flex it to remove the model.

The filament – which isn’t supplied – sits on a reel off to the left and is fed through a run-out sensor and a reverse Bowden tube to the extruder that feeds it into the hotend.

This can heat up to 260°C, some 40°C off the 300°C some rivals offer, but it should be enough to handle PLA, ABS and PETG. Anycubic also lists the flexible TPU filament as one of the materials the Kobra 2 Plus can handle, but if you want to use that, you’ll need to set much slower print speeds – around 100mm per second.

The included nozzle isn’t hardened so you can’t print with abrasive filament such as carbon fibre PLA.

The bed goes up to 90°C, which is again lower than some printers. But again, it should be enough for most people.

Do note that as this is not an enclosed printer you might need to put it in a cabinet if you want to print with ABS or PETG which need a constant ambient temperature that’s higher than normal room temperature to avoid problems with warping. This isn’t an issue if you’re just printing with PLA though.

Setup

The printer arrives in two main pieces: the base and the gantry. These are fastened together with 16 screws for shipping, which is unusual, so removing them takes a little while before you can start actually assembling all the parts.

Jim Martin / Foundry

The instructions that come in the box are good, though, and it took me about 30 minutes before I could power it on for the first time.

When you do this, you’ll be walked through choosing your language, connecting to your Wi-Fi network, installing the Anycubic app on your phone – where you need to create an account and then scan the QR code to connect the printer to your account so you can monitor it from the app.

Jim Martin / Foundry

After that, it’ll run through a self-test process, automatic levelling, loading some filament, and finally vibration compensation (which should be re-run whenever you move the printer to a new location).

Jim Martin / Foundry

You can then print any of the models pre-loaded in the 8GB of on-board storage. But I’d advise against that as they all have a brim by default which is a pain to remove for the articulated dinosaur and even the bottle opener.

It is the simplest way to test that the basics are working, but pre-sliced files aren’t always the best demonstration of the quality you can get.

I didn’t like the placement of the filament spool holder because it’s right by the ribbon cable for the print head, and the two touch when the print head is low down. It also means you need a lot more desk space compared to if the holder were placed on top of the printer.

Jim Martin / Foundry

You’ll need a lot of space anyway: the Kobra 2 Plus measures 630x605x564mm / 24.8×23.8×22.2 inches (HWD) and needs much more depth that to allow for the full travel of the print bed – at least 700mm.

Performance

I printed my usual selection of test files, slicing them using Anycubic Slicer – the company’s clone of the popular open-source Prusa Slicer – and using the PLA profile supplied on the USB stick.

It’s strange that Anycubic doesn’t provide more profiles for other types of filament, and there isn’t even one to cater for non-high-speed filament.

Jim Martin / Foundry

As you can see below, the default speeds aren’t anywhere near the 500mm per second maximum claimed speed, nor are they even the 300mm per second average speed that’s advertised. However, there’s nothing to stop you increasing them from these presets.

Jim Martin / Foundry

At these settings a 3DBenchy will print in just over 30 minutes. But the pre-sliced Benchy on the USB stick prints in under 20 minutes.

Jim Martin / Foundry

Using some high-speed grey filament that Anycubic sent for testing, print quality wasn’t the best at the default settings. You can see it’s not very clean at all on the side of the slug below. I tried various other prints and then swapped to some high-speed filament I had left over from testing the Creality K1 Max and prints were much better quality, suggesting Anycubic’s wasn’t as good. It certainly turned very brittle at the low temperatures in my garage of around 10°C.

Jim Martin / Foundry

Get the right combination of filament and settings – and slicer software – and the Kobra 2 Plus is capable of decent quality as this Benchy shows. It printed in around 30 minutes.

Jim Martin / Foundry

I like to test each printer’s tolerance with a few articulated models including this slug. At the default size, printers often end up fusing the segments together, which is exactly what the Kobra 2 Plus did.

A similar thing happened with some of the hinges on this infinite cube which also fused together. While a few of the hinges were simply a bit stiff, a couple wouldn’t budge and forcing them caused the plastic to break.

Jim Martin / Foundry

I thought it might be – again – old filament at fault, but I threw the reel into the Bambu P1S’s AMS and used the same 0.2mm layer height. No problems with fused hinges at all: the cube folded perfectly.

I then printed this tiny honeycomb box with a matching lid. Printing both parts at once proved too much for Anycubic Slicer which did warn me that there was a problem with the movement path which I ignored and ended up with a complete mess.

Jim Martin / Foundry

Printing them separately worked much better and demonstrated that the Kobra 2 Plus’s retraction is great: there was minimal stringing and the box looked great.

To test for any layer shift with large prints, I printed the double-spiral vase (shown in the photo at the top of this review) almost 400mm tall. I used some rainbow filament and ticked the spiralize setting in the slicer. It’s hard to say if the gaps at the bottom of each diamond are due to the filament not being specifically high-speed stuff, but the end result looks great.

Jim Martin / Foundry

It was also good that, despite a lot of “shaking” of the model as the print bed moved back and forth quickly, the vase stuck firm to the build plate, as did all the prints I tried. You may need use a glue stick if you want to print with ABS as you’ll almost certainly end up with some warping if you don’t.

In terms of noise, most of it comes from the powerful cooling fan. But the power supply also has fans and they were very noisy. I sent a video to Anycubic and asked if this was normal, and was told I’d need a new power supply, which would be provided under warranty. As of writing this review, that has not yet arrived.

App & cloud

In the middle of testing, Anycubic released a significant firmware update which added support for cloud printing and monitoring. This turned out to be a huge palaver, partly because I ended up somehow installing the firmware for the Kobra 2 Max and Anycubic’s support then failing to instruct me to put the correct update file into an Update folder on a USB drive and instead saying the file needed to be in the root folder where the printer completely ignored it.

Jim Martin / Foundry

However, the update should have been worth it as it means you can use the Anycubic app to find, slice, print and monitor progress of that print. The reality was much less impressive.

Printing from the app proved impossible. After choosing a model to print, the app remained on the slicing screen indefinitely and only when trying to cancel it did it move onto the printing screen, but the printer itself never seemed to receive the print.

Jim Martin / Foundry

I tried the same thing from the Windows app: using the cloud service to remotely print a model sliced in the app. But yet again, despite assurances that the gcode had been sent to the printer, no printing ever began.

It’s worth saying that you can’t monitor print progress from the desktop app – only the mobile one. On mobile it works fine, and sends notifications when there’s a problem (such as the filament running out) and also when prints are complete.

Jim Martin / Foundry

The firmware supposedly added support for webcams as well, so I tried plugging in three different cameras into the USB port marked with a camera icon. At least one seemed to be working, as it’s LED turned on, but there was nowhere in the app to view the camera feed.

Jim Martin / Foundry

Ultimately, I ended up exporting gcode from the desktop app to a USB drive and plugging that into the Kobra 2 Plus, then monitoring progress from the mobile app.

A slick experience it was not.

Price & availability

The Kobra 2 Plus costs £449 / $449 from Anycubic’s website . For Black Friday, there’s a £50/$50 discount bringing it down to £399/$399.

That’s a tempting price for a printer with such a large print volume, fully automatic bed levelling and high print speeds.

If you’re thinking about saving money and see the original Kobra Plus on sale, just remember that its build volume is smaller (300x300x350mm) and it is much slower.

For alternatives, see our recommendations of what to buy in our best 3D printer roundup.

Should I buy the Anycubic Kobra 2 Plus?

Yes, if you’re looking for a 3D printer that can print larger-than-normal models quickly using PLA. With decent quality filament, it can do a great job. Just bear in mind that it’s quite noisy.

If you don’t need such a huge build volume, consider the Kobra 2 Pro which takes up much less space and is quite a bit cheaper.

Then again, Elegoo’s Neptune 4 (or Pro) is also well worth a look for even less.

It was a shame that I had so many issues with the Kobra 2 Plus, from the overly noisy power supply fans to the inability to print remotely or see printing in progress using a webcam. Then there’s the fact that it’s not very good at printing when tight tolerances are required for articulated parts.

But if you don’t intend to print those sorts of models and are happy to transfer prints on a USB stick then the Kobra 2 Plus is a decent choice.

Best Prices Today: Anycubic Kobra 2 Plus

Author: Jim Martin, Executive Editor, Tech Advisor

Jim has been testing and reviewing products for over 20 years. His main beats include VPN services and antivirus. He also covers smart home tech, mesh Wi-Fi and electric bikes.

Recent stories by Jim Martin:

• The best 3D printers 2024
• Creality K1C review
• Bambu A1 review

Just a few years ago, 3D printing was a hobby for geeks and nerds. It was difficult, frustrating and slow.

Fast forward to 2024, and that has all changed completely. Now, you can buy – for a very reasonable sum – a printer that works out of the box, doesn’t require hours of tweaking and adjusting and prints large models in hours – not days. Small models can take mere minutes.

Since you’re reading this, you’ve probably made it past the point of wondering what on earth you’d use a 3D printer for, but if not, there are many useful tools and gadgets as well as fun things to print, all of which are available to download free from sites such as Thingiverse and Printables .

Here we’ll explain what to look for in a 3D printer and recommend what you should buy.

First, a brief word on colour: consumer 3D printers are single-nozzle devices which print one colour at a time. If you want to multicolour prints, then Bambu’s P1S Combo and A1 Combo can hold four spools of filament and change colour automatically. Multicolour prints can take a long time, though, and waste filament.

One other thing: until you’ve spent time getting to grips with a 3D modelling app such as Fusion 360 or Tinkercad , you’ll be limited to printing objects that other people have designed. There are lots of them, but if you want something bespoke, you’ll have to create it yourself.

Don’t be put off buying a 3D printer, though. Choose wisely and you’ll be rewarded with a device that can print intricate, articulated models from the off.

We’re focusing mainly on FDM (fused deposition modelling) printers here because these are the most popular type. The other type is a resin 3D printer, such as the Creality Halot One Plus, which works very differently, and are designed for printing small, intricate, solid models.

Best 3D printers 2024

1. Bambu P1S – Best 3D printer for most people

Pros

• Excellent print quality
• Automatic colour changing
• Fast CoreXY motion system

Cons

• Basic non-touchscreen control panel
• Filament wastage can be high in multicolour printing
• No failed print detection

With so many tech products you get what you pay for. This inevitably means the “best” will also be the most expensive. It’s certainly the case here, but just because the P1S is expensive doesn’t mean it isn’t good value.

If you buy the P1S Combo, it will come with an AMS, a unit that sits on top of the printer. It holds four spools of filament and can load and unload them automatically and print in multiple colours without any assistance from you.

With only one nozzle, multicolour prints aren’t exactly fast. But the AMS also takes the pain out of changing filament when you want to print something in a different colour to the previous print.

If you don’t care about multicolour, you can buy the non-Combo version of the P1S for quite a bit less.

Overall, the P1S is a remarkably good printer. It’s really fast thanks to the use of a coreXY system, and as it’s fully enclosed it’s reliable even when printing with ASA, nylon, polycarbonate and other filament types because of the stable internal temperatures. More importantly, print quality is absolutely superb.

If there’s a downside, it’s the rubbish dot-matrix screen which seems very out of place on a printer this expensive. But, there are other ways to control the P1S, such as printing from a PC or phone via Wi-Fi. The Creality K1C is a good alternative if you must have a touchscreen, and it also has a few other features such as failed print detection.

If you just want to print with PLA, PETG and other filament types that don’t require an enclosure, take a look at Bambu’s A1 which is a lot cheaper.

Read our full Bambu P1S Combo review

2. Bambu A1 – Best budget 3D printer

Pros

• Fast, reliable printing
• Fully automatic levelling
• Excellent value

Cons

• Doesn’t support more exotic filament
• AMS Lite adds significantly to the price

In our full review, we call the A1 “the 3D printer you’ve been waiting for”, and with good reason. It’s as close to ‘one click’ printing as you’ll get right now: it adjusts itself automatically for reliable printing and has all the features most people want, at a surprisingly affordable price. Bambu’s desktop and mobile apps are really good, too.

Like Bambu’s more expensive P1S, it can print models up to 256mm³ and you can buy the optional AMS Lite (shown to the right of the A1) for automatic multicolour printing.

The only drawback is that the A1 can’t really print nylon, ABS, ASA and other ‘exotic’ filaments because they require an enclosure. Without one, they tend to warp. The A1 can print carbon-fibre filaments if you buy Bambu’s hardened nozzle, which is very easy to fit.

Print quality, when using supported filament types, is sensational.

Read our full Bambu A1 review

3. Creality K1 Max – Best large 3D printer

Pros

• Fast, reliable printing
• Large build volume
• Fully automatic bed levelling

Cons

• Some features exclusive to Creality’s slicer
• No multi-colour capabilities

Some may say the K1 is just a poor copy of the Bambu P1S, but that does it a disservice when so many 3D printers are basically copies of each other. There are two models, the smaller K1 which is cheaper than the larger K1 Max.

The Max offers a 300x300x300 build volume, something not currently available from Bambu and it has an easy-to-use touchscreen. Bed levelling is fully automatic and it even has a LiDAR system that helps ensure prints are successful and good quality.

There’s built-in Wi-Fi and an ‘AI’ camera that can detect when prints are failing, as well as when you might have accidentally left a model or some tools on the build plate.

As both K1 and K1 Max use coreXY systems, they’re just as fast as the Bambu and although quality isn’t quite up to the P1S’s level, it’s still very good.

Read our full Creality K1 Max review

4. Elegoo Neptune 4 – Best cheap 3D printer

Pros

• Fast printing
• Automatic bed levelling
• Intuitive touchscreen controller

Cons

• No Wi-Fi
• More expensive in UK than US
• Elegoo’s slicer isn’t the best

The Neptune 4 offers everything most people are looking for in a first 3D printer. It’s easy to set up, has auto bed levelling, a colour touchscreen and is pretty fast to boot.

That’s already a lot for the low price, so it’s not too surprising it doesn’t have Wi-Fi. Unlike some of the budget models here, it competes with the coreXY printers for speed thanks to an upgraded print head with much improved cooling over the Neptune 3.

It’s a shame that like the Ender 3 S1 Pro levelling isn’t completely automatic, but once you’ve adjusted the knobs, subsequent levelling is automatic.

Print quality is very good at the default 300mm speed, but it’s a good idea to use an alternative to Elegoo’s slicer which caused us quite a few headaches when prints failed.

Read our full Elegoo Neptune 4 review

5. Creality K1C – Best for exotic filaments

Pros

• Can print carbon fibre filaments out of the box
• Can print ASA, nylon, ABS as well as PLA and PETG
• Built in camera

Cons

• Single colour printing only
• Can be very noisy
• Frustrating to change filament

The K1C can print models up to 220x220x250mm, and comes almost fully assembled. It’s fully automatic, which means there’s no need to make any manual adjustments: it prints reliably from the word go.

Effectively, it’s an upgrade of Creality’s K1 and has a hardened steel nozzle that can print abrasive filaments like carbon-fibre infused PLA and PETG. Unlike the K1 it also has a camera for monitoring print progress remotely, and it’ll detect and notify you of problems like foreign objects left on the build plate and failed prints.

The touchscreen makes it easy to use, and Creality’s desktop and mobile apps aren’t bad, although they lack the polish and ease of use of Bambu’s.

The only real limitation is that the K1C can’t print in multiple colours, but if you don’t need to do that, it’s a great choice.

6. Anycubic Kobra 2 Plus – Best for printing huge models

Pros

• Massive build volume
• Fast

Cons

• Takes up a lot of space
• Not suitable for filaments which require an enclosure

With a build volume of 320 x 320 x 400mm (WDH), the Kobra 2 Plus can print very large models. If that’s not enough, there’s also the Kobra 2 Max with an even larger 420 x 420 x 500mm volume.

It’s a bed slinger, which means the build plate moves backwards and forwards. In turn, this means you need quite a lot of desk space for the Kobra 2 Plus. It’s fast and capable of good print quality, and is pretty easy to use thanks to automatic bed levelling, vibration compensation and a colour touchscreen.

Read our full Anycubic Kobra 2 Plus review

7. Creality 3D Ender 3 S1 Pro

Pros

• Great print quality
• Almost all the features you’d want

Cons

• Auto-levelling requires manual input
• Slow by today’s standards

The S1 Pro is really a budget 3D printer but it’s more expensive than the cheapest because it has had all the bells and whistles thrown at it.

There’s the Sprite direct drive print head with dual metal gears for reliable extrusion. It’s capable of heating to 300C, so you can print with a wide range of filaments. The bed goes up to 110C, too, which helps prints adhere when working with more awkward types of filament.

It isn’t enclosed, though, and is a bed-slinger, so needs room in front and behind it to accommodate its range of travel. There’s a useful LED strip which is really bright, and a colour touchscreen. Its interface could be improved a bit, but it’s not bad.

Print quality is very good, but it isn’t fast. To improve it you can buy Creality’s Sonic Pad – a Klipper-based touchscreen – but this adds a lot of cost and hassle. If speed is important, choose a printer that offers 300mm/sec out of the box like the Bambu A1.

Read our full Creality 3D Ender 3 S1 Pro review

8. Creality Halot One Plus

Pros

• Easy to use & reliable
• Works with various slicers
• Great print quality

Cons

• Fan runs constantly during printing
• Requires post-printing cleanup + curing (like all resin printers)
• More expensive than some rivals

The Halot One Plus is an easy-to-use resin 3D printer that has a good-sized build volume, prints reliably and at high quality. It’s quite expensive compared to rivals, especially in the UK.

The Halot One Plus is a resin printer, so is very different to the others here. Instead of using filament on a reel, it prints using liquid resin which is cured, layer by layer, using UV light.

Build volume is smaller than the FDM printers here, but it’s still relatively large for a resin printer, and the screen’s high resolution means models have lots of fine detail.

The Halot One Plus printed ultra-reliably in our tests, but if you are keen on a resin printer, bear in mind that you have to clean up prints afterwards, which usually means buying a separate washing and curing device that looks a lot like a resin printer and takes up the same amount of desk space.

Read our full Creality Halot One Plus review

Buyer’s guide

Here are the key things you should look out for when choosing a 3D printer.

Automatic levelling

Unless the surface on which objects are printed is perfectly level, prints won’t stick to it and will fail sooner or later.

Manual levelling is a chore you could do without, so go for a printer with auto levelling. Be careful: some printers claim to have auto levelling, but rely on you to do a lot of the work. Which is why it pays to read reviews as well as knowing what to look for.

Heated bed

Almost all 3D printers have them, but it’s a must have. A heated bed will help prints to stick: don’t buy a printer without one.

PEI sheet

Models can be difficult to remove from the build plate. A PEI (polyetherimide) sheet helps immensely. It’s a flexible metal sheet with a textured coating is used, and held in place with magnets. When the model finishes printing, you simply lift the sheet off, flex it and the model pops off.

Touchscreen

Some printers still use a monochrome screen with a rotary dial or buttons. This isn’t nearly as easy to use as a touchscreen. Bambu P1S (and P1P) would be much better with a touchscreen, but it’s not the end of the world with those as you can print from your PC or phone using Bambu’s apps. When a printer doesn’t have Wi-Fi (or any networking) you are stuck using the screen it comes with.

Build volume

A printer’s build volume tells you how big an object it can print. It’s wise to assume that the actual maximum volume is a bit smaller than the specifications suggest, and go for one with a slightly larger volume than the biggest object you will need to print.

It can be hard to know this, and remember that a bigger volume means a bigger printer, which you’ll need space for.

Really large models can be printed in sections and superglued (or otherwise fixed) together, so you don’t necessarily need a huge printer.

Nozzle and bed temperatures

Most people print using PLA, the most common type of filament. It’s easy to work with, strong and durable.

All 3D printers have nozzles that go up to the 220°C or so that PLA requires. But if you want to print with ABS, PETG or another type that needs high temperatures, be sure to opt for a printer that can go up to around 300°C. But see Enclosure below, too.

Similarly, watch out for heated bed temperatures. Some won’t go beyond 80°C, but you’ll need 100°C or more for successful ABS prints.

Enclosure

Some materials such as ABS, ASA, polycarbonate and nylon need carefully controlled ambient temperature to prevent them from warping while printing. If you need to use these – perhaps because you want to print models that can survive exposure to sunlight, then look for an enclosed printer – essentially a self-contained box.

Run-out sensor

With large models taking many hours to print and the fact that you can’t always know if there’s enough filament left on the reel to complete it, a run-out sensor can be a life saver. It does it what it says: detects when the filament runs out and halts printing automatically, allowing you to load a new reel and carry on printing.

Without one, the filament could run out and the printer will carry on printing thin air, and you’d be none the wiser.

What’s the best 3D printer for beginners

The Bambu A1 is an excellent choice for beginners. It’s relatively affordable and is very easy to use because it handles so many things automatically. It’s also fast and offers top notch print quality.

How much does a beginner 3D printer cost?

Printers start from as little as $130 / £130, but you may want to spend more to get a better model with more features, faster speeds and better print quality. There are a lot of great printers under $500 / £500.

What type of 3D printer is best?

The most common type is FDM (printers that use filament on a spool), but the absolute best quality is from SLA printers, which use resin and are capable of printing much finer detail. There are lots of pros and cons of each type, but put simply, resin printers are best for small, intricate figurines, while filament printers are best for printing things that are useful around the home as well as models that hinge or articulate.

Is it cheap to use a 3D printer?

Spools of filament typically weigh 1kg and cost from $15 / £15 to $30 / £30. It’s therefore the weight of the model that matters most, not the size. So-called slicing software turns a 3D model into instructions a 3D printer can understand, and you can adjust the settings to save weight by minimising the amount of infill. Sometimes it’s cheaper to print your own parts, but sometimes you might find it’s cheaper to buy pre-made plastic things than to 3D print them.

Are 3D printers good for beginners?

3D printing is much easier than it used to be thanks to modern printers that automate a lot of the fiddly things like bed levelling. They can also compensate for vibrations, resume printing after a power cut or when the filament runs out. The difficult part is designing your own models to print, but there are thousands of pre-made models available online to download free.

Author: Jim Martin, Executive Editor, Tech Advisor

Jim has been testing and reviewing products for over 20 years. His main beats include VPN services and antivirus. He also covers smart home tech, mesh Wi-Fi and electric bikes.

Recent stories by Jim Martin:

• Creality K1C review
• Bambu A1 review
• Bambu A1: a full-size bed slinger 3D printer