Example filament extruder from PLA/ABS pellets from Hugh Lyman.
Jose Manuel Dias Luís had his first electronics classes at FAP and then studied electronics engineering at UALG where he created an electronics club. Lives in Algarve and made his first radio receptor when he was 10 years, and ever since then never stopped doing things, some with electronics, some with mechanics.
For the Maker Faire Lisbon he built his own filament extruder from ABS or PLA pellets. The extruder gets PLA or ABS from low cost pellets and then extrudes the filament. The extruder has a heat resistor controlled by a PID controller so it can keep a constant stable temperature for the machine to work properly.