Circuit Playground Yo-Yo

Update: Adafruit created a version of this project that doesn't need hardware! Check it out here: http://www.thingiverse.com/thing:1766385

Create a programmable yo-yo using Adafruit's Circuit Playground and these 3D printed parts. The assembly is snap/press fit.
For the full instructions check out the Google Doc linked below.
For scaling/dimensions - scroll through the photos above. All dimensions are in inches.

To print this project, you'll need to print two yo-yo body parts along with two snap rings. You'll assemble the yo-yo using an M5 nut, spacer, and hex head screw. If you press the nut and the hex head screw into the plastic while it's still warm, it's a lot easier. Forgot and let the print cool? No problem, just use a little more muscle.

Full CAD via OnShape here:
https://cad.onshape.com/documents/a10dec4ede7ddb8cb4bf5b27/w/f8c0332f02fca9a2d04ad0e7/e/40577b039709625f2ac633fe

Live documentation (I'm updating it 7/29/16) here:
https://docs.google.com/docu