Do you remember how my circuit looked before? It was basically just components on a breadboard, connections made with jumper wires, and a tiny power bank to supply power.

Now it looks like this:

I switched from an Arduino Pro Micro to a Seeeduino XIAO simply because I had a few on hand and wanted to make the final board as tiny as possible (it's only 40 x 60mm). The 7805 package size is definitely overkill for this circuit, but that was the only through-hole 5V regulator I had lying around.

I also ordered a tiny plastic case on Amazon, which should be delivered next week. I’ll finish the project with a log of the complete product.