Flipper Zero ProtoBoard case/cover

This is a simple case or cover for the [Flipper prototyping board ("ProtoBoard")](https://shop.flipperzero.one/collections/flipper-zero-accessories/products/proto-boards) with 10mm of clearance on the "top" and 5mm of clearance on the "bottom."

I needed a simple, open cover for my [prototype VOC monitor module](https://github.com/thzinc/flipperzero-firmware-voc-monitor/) for the Flipper Zero.

The case comes together with M3 heat-set inserts and 16mm long M3 bolts.