Hypocycloid How To (25:1 example)

This Thing includes complete design files in OpenSCAD and instructions for customizing to your own needs. There is a set of stls which can be printed to produce the example shown in the videos. Note that the zip archive provides some files not listed separately. Have a look at video here: http://youtu.be/NP0ElIfxF14
The inspiration for this Thing was Thing 43176 and the first section of video is of my build of Thing 43176 in action. It provides about a 50:1 reduction. In the video, you can see that the output slows the drill down a lot. To build this, I had to reduce the rotor stl 98% with netfabb, then enlarge the bearing mounting ring with a Dremel. Pretty cool result, but three things were lacking. First, it's too big – bigger than the NEMA 14 I wanted to mount it on. Second, the gear ratio is too high. Third, the output shaft is M8; I'd like it to be M5.
Looking for more information, I found Thing 8348 and Thing 19649. While these provided very useful pointers to hypocycloid