Disposing Of PLA And Why Composting Is Not An Option

October 16, 2026 by Maya Posch 28 Comments

The ‘biofriendly’ nature of poly(lactic acid) (PLA) filament often gets touted as one of its main advantages over alternatives like PETG, but even a modicum of research ought to inform a person that the biodegrading feature of PLA is only true for pure PLA without additives and at temperatures at or above its glass transition temperature (Tg). Thus the results of a year-long experiment by [I built a thing] shouldn’t be too surprising.

After burying said PLA in the garden like any self-respecting person does who tries to dispose of some evidence, the PLA suffered through a European winter and very hot, dry summer, before being dug up again recently for inspection and testing. Although not the first time that someone has tested this, it’s a good reminder considering just how much PLA filament is used each year.

In total three sample sets were used, one being the control, the other two buried in soil and compost respectively. A visual inspection showed no major difference, and a tensile strength test also showed no statistically significant change among all three sample sets. The experiment could have been concluded here, but instead calorimetry was used in a laboratory setting to see whether exposure to microbes as commonly found in soil does anything significant.

This isothermal microcalorimetry test was performed at the University of Basel, effectively to answer the question whether there’s anything in the PLA samples that can feed said microbes. As it turns out, the answer is a resounding ‘no’, with microbial activity within the presence of PLA dropping off even quicker presumably due to there being less volume available for nutrients.

When [I built a thing] contacted a large number of commercial biodegrading facilities in Switzerland, Germany and the USA, many would happily take PLA, but none of them would accepted 3D-printed PLA parts, which says a lot. The primary reason for this appears to be that even under industrial composting conditions it simply takes too long for these facilities to consider these to be economical to compost.

With PLA primarily degrading via hydrolysis, it needs to be exposed to the right conditions for this process to not take an eternity. You can of course use something like PHA instead, which doesn’t require this hydrolysis step to be biodegradable. Overall PLA is quite a crummy material, with it also suffering from embrittlement due to crystallization that will happily turn a spool of PLA into lots of sad fragments. This makes PETG into a very common and very attractive alternative to PLA.

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Rendering 3D Prints From G-Code

October 14, 2026 by Zoe Skyforest 22 Comments

Your CAD software generally has some rudimentary tools for rending images of your parts, from simply-textured models to more photo-realistic options. However, those renders are of the geometry you created—not how that geometry would look after it was sent to a 3D printer. Extrudio is a tool that aims to create more realistic renders for 3D printed parts.

Rather than rendering from the geometry of your model, such as by using an STL file, Extrudio uses G-Code instead. It creates its render based on the instructions your 3D printer uses to produce your part, sweeping a virtual bead of plastic along the toolpaths in the code. In doing so, it can realistically display layer lines in a 3D print and other artifacts of the printing process, like stair-stepping on spheres and curves. It can display the render in various contexts, from blank studio backgrounds to a number of “sets” like a bench or kitchen.

The tool’s website notes that this could be useful for generating images for those selling 3D printed parts online, though obviously the realism of actually printing and photographing a part would still be superior. Still, it could prove a useful tool for quickly pitching realistic images of a 3D printed part, particularly if it’s desirable to model different colors or print techniques without putting in the hours to actually produce them.

We’ve featured some other great 3D printing hacks lately, like this nifty trick for doing overhangs without supports.

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Counting The PET Bottles Needed To Make 1 Kg Of Printer Filament

October 13, 2026 by Maya Posch 33 Comments

In countries where PET bottles do not get slapped with an additional fee that induces you to return it for recycling and said fee back, the resulting piles of discarded bottles have led many enterprising individuals to consider using them to make their own PETG filament. One big question of course is just how much work it is to create even a single 1 kg spool of PETG, which is a question that [PETCraft] was only too happy to answer in a recent video.

With the channel owner clearly living in a country without a bottle deposit, it’s very easy to see PET bottles strewn about as trash, including multi-liter water bottles. As a very recycling-focused channel, this provides an excellent opportunity to show how they go about recycling these into filament.

The heat-smoothed water bottles, ready for cutting.

The detailed process is covered in previous videos in the channel, but essentially they are first heat-smoothed to make them much easier to cut into thin strips. This is done with a very DIY cutter – also constructed from mostly salvaged and other common parts – before the strips are passed through the heated extruder nozzle of the DIY filament extruder before being wound onto spools.

Ultimately it took thirteen 5 liter bottles, a 10 L, two 8 L and a single 1.5 L bottle to hit the 1 kg target, which is quite an impressive amount of work. The next challenge will be to actually print with it, which will – naturally – be done with a DIY 3D printer made from salvaged parts and an Arduino board.

The good news about recycling bottles like this into filament is that basically all PET bottles will actually be PETG anyway, as the glycol adds the flexibility that’s essential in water bottles so that they do not shatter or rip easily. The real question you have to ask yourself is whether cleaning, cutting and spooling dozens of bottles is worth saving perhaps 10-20 bucks on a commercial spool of 1 kg PETG filament.

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Using Kirigami Techniques To Make Functional Designs

October 12, 2026 by Maya Posch 11 Comments

The variant of origami called kirigami (‘cut paper’ in Japanese) also starts off with a sheet of paper, but it allows for cutting the paper to increase the number of shapes that you can create. It is this technique that [Matthew Lim] used to create a number of three-dimensional designs that can convert between a flat configuration and some kind of functional object without any bolts, glue or similar. These include everything from a phone grip to a pretty sizeable side table.

The video starts with an interesting demonstration of how to fold an origami crane that has a smaller crane on its back. This is documented in a 1797 book on the many ways to fold a crane, with one of the first known instances where cuts are made in the single sheet of paper, which becomes the second, much smaller crane.

The same book extends that idea into making an origami grid that can fold into a grid of cranes after making a series of cuts. Later this form of origami got the name ‘kirigami’, with the video demonstrating how a few strategic cuts in an original flat shape can make it much more functional, based on scientific papers like this 2024 one by [Liu] et al. on cylindrical origami with tunable mechanical behavior.

For these functional mechanisms a laser cutter and FDM printer are used to prototype and test increasingly more advanced versions of the pop-up mechanism, before moving on to make full-sized furniture using plywood panels and 3D printed hinges. The coolest part about the resulting table is that it can be changed into different configurations, with the mechanism locking into its new position to make a relatively stable new shape.

Even if not immediately practical, these mechanisms provide interesting options for robotics and flat-pack furniture alike, as well as in applications like space exploration where every gram and cubic millimeter of space counts.

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The Prusa Core One+ INDX, A Troubled Multi-Extruder Upgrade?

October 12, 2026 by Maya Posch 15 Comments

The Prusa Core One+ INDX is an interesting upgrade to the base FDM printer by Prusa, featuring eight independent extruders – hence the INDX – that in theory should allow for multi-material and multi-color printing with very little purge waste. As [Thomas Sanladerer] found out during his experiences with this printer, there are a lot of issues with this machine, including the ability – or lack thereof – to print with non-Prusa filament.

Although the premise is solid, with a claimed 0.013 grams of purge waste per color or material change along with pretty nice dual-gear Bondtech extruders, the first major hurdle that [Thomas] encountered was that the mandatory calibration sequence on starting a print is designed to only work with Prusa’s own filament and its specific material properties. This resulted in an inability to print with Voxel PLA until [Thomas] removed this sequence manually from the g-code.

This is when [Thomas] found out that the entire print sequence uses the material presets for Prusa’s filament, resulting in a failed print. The results from the manual calibration are also not saved despite the display claiming it does, making this calibration on starting a print absolutely mandatory.

Other issues found are the useless position of the camera as it’s now blocked-off by the INDX hardware, with even manual peeking into the print chamber being heavily obscured by the contraption that holds the extruders. This makes even checking that filament has loaded correctly is borderline impossible, never mind ogling the printing process.

Although there’s a lot to like about this INDX upgrade to the Core One+, the above and other issues discussed in the video make it look somewhat shaky next to competitors like the Bambu Lab H2C and Snapmaker U1, as well as Prusa’s own XL toolchanger printers. During [Thomas]’s print test comparison between the XL and the Core One+ INDX there was no contest that the XL simply works, whereas the INDX even struggles with some Prusa filaments.

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Embedded 3D Printing With Liquids On A Bricked Prusa FDM Printer

October 9, 2026 by Maya Posch 6 Comments

Recently [Riley] got his paws on an old Prusa i3 FDM printer that had clearly seen better days, with a hot-end that had suffered an explosive blow-out. For the project he had in mind this was of course perfect, as his intention was to replace the hot-end with a syringe system for embedded 3D printing (E3DP), which uses a supportive medium to allow for the printing of materials and structures that would be impossible with just air.

Generally in additive manufacturing (AM) methods like fused deposition modelling (FDM) the material is extruded onto a build plate or a previous layer where it solidifies. This works great for materials like thermoplastics, but for other materials having only the surrounding air as support is just a recipe for a big mess. With E3DP the liquid is instead extruded into a supportive material at a selectable depth and volume, opening up a whole range of possibilities.

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A Headset Fit For A Hackaday Writer

October 6, 2026 by Jenny List 22 Comments

I started writing this from a commuter train passing at speed through the outskirts of London, and my headset had just broken. The flexible joint that attaches one earpiece to the headband has snapped, leaving the earpiece dangling on its cable. This is annoying on its own, but what is annoying me enough to write about it is that this isn’t the first time. This is only the latest in a succession of headsets I’ve taken on the road with me has broken, not because of rough treatment, but simply due to flimsy or bad design. What on earth can I do about this?

Failure Built-In

The earpiece of an EPOS headset, detached from its band. — Failure inevitable: the whole headset relied on a tiny piece of plastic in the centre.

The most recent three have been a JVC whose rotating joint allowing the earpiece to lie at a slight angle with my ear has failed, a quite expensive Logitech whose ear sponges failed closely followed by its USB cable, and now an EPOS whose ball joint has failed.

I repaired the JVC and got a bit more life out of it and I’ll have a go at repairing this EPOS, but that’s hardly the point. I’m paying not inconsequential money and I’m getting good sound quality and electronics, but I’m not getting anywhere near the mechanical quality I need. I could buy a set of tough DJ headphones such as the Sennheiser HD25, but they don’t come with a microphone, they’re not a headset.

So if I can’t buy a decent headset without spending military grade money on one from an F16 fighter, what can I do to make my own? I’m an engineer, damnit!

At its most basic, a headset is a springy band that goes over the head, with an earpiece at its end. But a human head is not a cube with vertical parallel sides, it’s a complex shape and every one is different. So those earpieces have to have some “give” in them in order to fit comfortably against the ear. In the simplest case this is achieved by giving the earpiece a soft surround that moulds itself to the ear, but most headsets incorporate some articulation. The earpiece must rotate a little around a vertical line parallel with the ear, and also with a horizontal line at right angles to the axis of the ear. The EPOS managed both axes by means of a ball joint, while the JVC had a stirrup with pins to achieve the horizontal motion, and a circular joint — the part which broke — for the vertical. In both case the weak point was a thin part of the plastic moulding which broke, on the EPOS a short stalk for the ball in the ball joint, and in the JVC a similar stalk for the circular joint. Any design I come up with must avoid this type of weak point, and spread the load of an earpiece over considerably more material than my broken headset. Continue reading “A Headset Fit For A Hackaday Writer” →