Clean up root dir
Simplify before making changes
Attempting simplification, more parameterization
Simpler design, handle nema17 motor better

Also, move extruder shaft closer to hotend to reduce the amount of
distance filament has to travel inside the extruder
Make sure bridges reach each edge
Groove for idler
Material savings
Avoid odd crevice; align things better
Make slic3r happier by removing a hole
I'll probably use a full-length nema17 at first