I started tinkering with this idea years ago and just found this stuff in a box so I thought I'd take some photos and ask what ya'll think. It's a crude prototype just meant to relay an idea. I'm just putting it out there in an open source sort of way so anyone that wants to run with it go ahead. Let me know if you have any questions. It's a lot further along in my head than it is in reality. If you're really serious about developing it into something I can buy someday I'll even send you all my prototype junk. We start with an epoxy battery holder that I molded from the grip cavity. Space enough for up to 3 2032 coin cells (G23 grip) in parallel for 3VDC. This needs a micro USB plug to transfer power up through the hole at the top of the cavity into the bottom of the trigger block. A micro lever arm switch is epoxied into a cutout in the trigger block. In this location the side of the cruciform that's attached to the trigger bar holds the lever in the forward position. The switch is spring loaded to snap closed when the pressure from the striker hook is relieved by pulling the trigger less than 1mm. Wires are connected to the common and N/C terminals of the switch and routed through channels cut into the block. They should run 1 each to the bottom of the block under the pin and the part of the block that sticks up into the rear cover plate. Probably the trickiest part of the whole system to envision. Making this part isn't easy without plastic molding equipment so I never made it. It's a pair of gold plated spring loaded contacts that transfer power from the trigger block up into the rear slide cover plate. I drew them on the cover plate rather crudely to show the general idea. The contacts would provide a circuit pathway whenever the slide was fully forward.