Footswitch interface case

This is a case for a USB footpedal interface I made. The Arduino code is here: https://github.com/monroewilliams/footpedal

It's intended to hold a mini breadboard (with a hole exposing the USB port on a microcontroller plugged into the board) and a variable number of 1/4" panel-mount TS or TRS jacks.

The number of jacks is configurable in the OpenSCAD file via the `jack_count` variable. If you set the number of jacks below two, the breadboard won't fit anymore.

The `usb_h` and `usb_v` variables set the location of the hole for the USB jack, you may have to fiddle with the numbers to line it up with the plug on your breadboard/controller combo.

I didn't add any specific features to hold the lid closed, but in my prints it stays on quite well as just a friction fit.