Some parts that I have printed, use, and recommend, that were modeled by friends of mine or by me:
Functional:
- Redrawn filament drive with filament guide, beefed up outer screw holes, adjusted gap spacing, and increased coning on lower filament hole, for v3b and E3D hot ends: http://www.thingiverse.com/thing:267137
- SD card reader housing, less rattly than the stacked laser cut housing: http://www.thingiverse.com/thing:295163
- Webcam mount: http://www.thingiverse.com/thing:265276
- Prettier z-knob: http://www.thingiverse.com/thing:266807
- Z-axis stay for the above: http://www.thingiverse.com/thing:267185