This is the old version, for the 3d-printed parts that require removing the crystal from the sound card. If you want the newest version, go here.
This part is optional, but very helpful! I will show how/where to cut holes for your micro USB charging port, power switch and L/R buttons. But if you'd like to make it a little more foolproof this guide helps a lot: snap it to the bottom of an altoids tin and mark exactly where you need to drill/file. Easy-peasy. :)
Price is $5 + shipping/paypal fees.