I added the current working version of the schematics. I've been testing these designs with no issues. I also added a parts list, here's a link to the project on the Mouser website where I get my parts: 

https://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=a8b03ec8d2

Parts come in at $15.52 not including the battery

Here's a rough wiring diagram to give you an idea of how the mod works

The final battery is actually 700mah. With the current hardware I estimate a 6 hour playtime but haven't timed it irl. I currently can play a couple hours/day for 3-4 days before needing a charge.

Coming soon:

I'm making some final adjustments to the board shape so expect to see the PCB files soon. I get my boards from OSHPark, the design has been no problem to manufacture.

Stay tuned for when I release my code and my plans for manufacturing and distribution...