I've always loved motors. I had the nutty idea to design an "open source" motor that could be printed and built using nothing more than magnet wire, some patience and a few off the shelf components like skate bearings and the like. I developed a parametric openscad script for designing the coil forms and structure of the motor, printed a few pieces then got pulled away. This is what I was able to complete. The idea was this was to be a simple 3 phase induction motor. The electronics required to drive it would be complicated, but the motor itself is dirt simple, 3 coils and a core. The SCAD script generates all the pieces.

print 2 endplates and the forms. Wind the forms with magnet wire and place a solid electrically conductive (does not have to be magnetic) core within the forms, preferably with small shafts to support it on either side. If you dont want a working motor, you can also print the armature (add support for the bottom shaft) and you have all the pieces of the "open motor". There are also some blank winding forms under "motor.stl" for fun.

My hope is that someone will be inspired by this, and take it one more step : )

BTW, there was some gnarly math to get the endplates to look like that, intersecting circles at specific points and all that ... :D