Shaft Adapter (5mm -> 1mm)
I used this simple thing to help get a motor shaft onto a design with a larger interior hole. The interior is a 1mm triangle that can be bored out into a circle (it's done as a triangle to allow more accurate dimensions on a range of printers [see http://hydraraptor.blogspot.com/2011/02/polyholes.html]). You can modify the outer diameter and shaft length in the scad file.