In May 2012, a contest dubbed the “Desktop Factory Competition” offered $40,000 to whoever could come up with an open-source machine capable of turning plastic pellets into filament (suitable for use on a desktop 3D printer). The rules also stated that the parts for this device should not go over $250.
The 40k bounty was alluring, attracting Hugh Lyman, an 83-year-old enterprising inventor. Lyman’s first entry was the Lyman Filament Extruder, which was capable of turning inexpensive plastic pellets into new filament, as required. Unfortunately, this machine was disqualified for failing to come under $250. That’s because Lyman had used fabricated parts that he couldn’t account for.
Soon, the inventor was back with the Lyman Filament Extruder II, an update to the disqualified version. In addition to other material changes, it featured fewer wooded parts in favor of steel and impressed the judges enough to make Lyman the winner.
This hand-cranked extruder received mass acclaim for being simple and cheap in a niche market that mostly features expensive products. It was meant to process PLA and ABS pellets, but it can also recycle post-consumer plastic waste products.
Here’s how it works: You fill a hopper with your pellets and turn on a heater. The contraption melts the plastic pellets into molten plastic, which is then squeezed through the nozzle as filament. The coiling can be done on the floor.
The BOM includes quotations of custom parts, but this machine can dramatically improve the economics of 3D printing, saving makers up to 80% on material costs.
The Lyman Filament Extruder II is open source, which means that other makers can modify or improve its mechanisms if they want to lower cost or increase efficiency. As such, you can find a simplified version by Marcin Jakubowski and an improvised version by Lyman himself.