I wanted an enclosure to protect and disguise the main board on my printer. I couldn't find one I liked, so designed my own.
To install it, you'll need 4x 40mm M3 bolts. If you fit them from the rear acrylic mounting plate, through the supplied 4mm spacer, through the board and secure with an m4 nyloc nut, you will have enough thread left to slide the case up, and be able to secure it with 4x m3 nuts and washers. The reason it's designed this way is that if the case has to be removed, the mother board is still held in place.
The case is designed to hold a 40mm PC fan in the centre of the board. The tolerances are close, so if you follow the instructions above, you'll be fine.