USB AA battery shim

I had a [USB Micro-B Breakout Board][adafruit-usb] from Adafruit and a variable voltage buck circuit that were each mounted on convenient 10mm x 20mm PCBs that could easily fit within the bounds of a AA cylinder. The voltage buck is accessible to adjust the output voltage as desired.

I designed a holder for the two boards that allowed a USB micro plug to attach in the middle of the "shim" design, and made room to attach stuff with heat set inserts. The micro USB board is secured using M2.5 heat set inserts and the end contacts are secured with M3 inserts.

[adafruit-usb]: https://www.adafruit.com/product/1833