This is a case for the XY-LUP, a fairly uncommon USB step up / step down power supply.
The device is pretty useful, but I didn't like handling it without a case.
There are markings on the bottom that show what the connections are ~/-/+
The top case presses the motherboard down, and with a dab of glue they stay together.
The walls of the case are 1.6mm wide, so print with a wall thickness of .8mm and they will be solid.
This is the device that i used, you can find it much cheaper bought from china.