Imagine pouring a scoop of tiny plastic pellets into your 3D printer the same way you'd refill a coffee maker — no spool to load, no tangles to fight, no half-used rolls cluttering your desk. That is the dream behind granule (or pellet) 3D printing, and a hobbyist tinkerer has just pushed it one step closer to your benchtop.
What's the news?
A maker working under the name HomoFaciens recently shared the seventh version of a Direct Granules Extruder, an experimental tool head that swaps filament for raw plastic granules. The new build addresses a long-standing problem with earlier versions: hot plastic creeping back up into the cold zone of the extruder and gumming everything up. The fix involved water-cooling the upper section, fine-tuning the auger (think of a tiny wood screw that pushes pellets downward), and dialing in how quickly the granules melt before they reach the nozzle.
Why pellets at all?
Filament is convenient, but it is also expensive per kilogram and limited in flexibility. Pellets are the same raw material filament is made from, just one production step earlier. They cost a fraction of the price, and you are not stuck with whatever diameters or stiffness profiles the filament market offers. For schools, prop makers, and anyone printing big sculptural pieces, the savings stack up fast.
How does it actually work?
A small hopper sits on top of the extruder and feeds pellets into a heated barrel. An auger turns slowly, dragging the pellets down past a heater band where they melt into a continuous stream of plastic that exits through a regular nozzle. Tuning the auger speed is roughly equivalent to setting flow rate in your slicer — too fast and you over-extrude, too slow and you starve the nozzle. The test bench in this build uses a Prusa MK4, with the stock extruder swapped out for the experimental one, and early prints already look surprisingly clean.
Try it on your printer
You will not be retrofitting a granule extruder onto your Ender 3 or Bambu A1 this weekend — the hardware is firmly in DIY territory for now. But you can absolutely print the brackets, hoppers, and motor mounts that experimenters like HomoFaciens use, with bog-standard PLA or PETG on a 0.4 mm nozzle. If you want sturdy parts that handle a little heat near the motor, grab a roll of PETG from flarelab.com and print at around 240 °C with a 60 °C bed. Treat it as a great rainy-afternoon project to learn how extruders really work.
Frequently asked questions
Is pellet printing cheaper than using filament?
Yes, often dramatically so. Raw plastic pellets typically cost a third to a fifth of what spooled filament costs per kilogram, because filament is just pellets that have been melted, extruded, and wound onto a reel. The catch is that you need a special extruder to use them.
Can I bolt a granule extruder onto my Ender 3 or Bambu A1?
Not as a plug-and-play upgrade today. Current granule extruders are heavier and bigger than filament hot ends, and they need their own auger motor and cooling. Treat them as a serious DIY project rather than a kit you can install on a Sunday.
What kind of plastic do granule extruders use?
Most experimenters start with PLA or PETG pellets because they melt cleanly at familiar temperatures. Some advanced builds also handle TPU, ABS, or even recycled shredded plastic, but those usually need a tougher auger and more refined heat management.
Will the print quality match my filament printer?
For now, expect slightly rougher surface finish and less consistent flow than a tuned filament setup. Granule extruders shine on big, bold parts where speed and material cost matter more than fine detail. As the tech matures, that gap is shrinking.
Is this the same as recycling plastic at home?
It is closely related. If you pair a granule extruder with a shredder, you can in theory turn failed prints and clean plastic scrap into new prints. Just be aware that mixed or contaminated plastics can clog the auger and produce weak parts.
Inspired by reporting from Hackaday 3D Printing.
