10.
LiPo battery box (160mAh and 350mAh for the electronics bay
If you're familiar with Fusion 360 I included the f3d files on Thingiverse. You can easily rescale the box for any LiPo by adjusting the parameters (Modify, change parameters). The box is made so that a small Ty-wrap can be wrapped around and hold the batteries securely. Two batteries fit if you want more current. 4-40 screws hold it to the bay (or epoxy). Screw heads are sunk below the floor of the box. In theory you could fill the holes with epoxy and that would add a little strength. I'm going to use screws (maybe with epoxy).
I'm using a Featherlight switch, Altus Metrum "brains", and a LiPo to make it all work. I made a couple of circuit boards to go inside the Av bay to clean the wiring kludge. Once the boards get here I'll install the board, box, "brains" and post a pic (maybe not here). It'll be plug and play when I'm done.
All sliced up and ready to print one of each
Larger board circuit board. Functionally same as the small one but takes up more space
Smaller board. Same function. Not that BATT and CHG are common so you can plug in two batteries or just one and use a charger. The SW connection was intended for the Featherlight magnetic switch but a 2-pole "conventional" switch will work if you use the two outside pins.
If you're interested in the files just PM me. I used Eagle to make the schematic and board files so you'll need that. Osh Park will take the board files. I should have some boards back next week. ST connectors are already here