While I was constructing my board, I erred in using a test board which was designed and milled by Tim Fallon. A previous version of this post included an image of Tim’s board and has been removed.
The FabISP is an in-system programmer which lets you program microcontrollers with only a USB cable and a 6-pin to 6-pin cable. I followed this guide pretty closely to fabricate the board.
Building the board is just three steps: