Pricerange: $ 00.00

http://reprap.org/wiki/RepRap_Universal_Mini_Extruder

• 1.75 mm filament
• Adaptable mounting plate to attach it to virtually any 3D printer
• Very compact high-torque NEMA 11 motor
• Active ducted fan cooling for high reliability
• Wade-style hobbed bolt filament transport
• Wing-nut drive to spread the torque loading on the plastic gears
• Push-fit hot-end parts - no thread cutting
• Easily replaced PTFE liner for the hot end
• A single M3-threaded rod cut to lengths makes all the fixings
• Lightweight: 330g (about 50% the weight of this extruder)
• Compact design (110 mm x 90 mm x 80 mm)

I based this design (loosely) on Jstkatz's extruder on Thingiverse, in particular, the idea of using a lever to trap the filament against its drive.