I spent few hours today for building a simple case. I used spare parts and leftover in my workshop.
It's in early prototype stage.
The board is mounted on a steel plate with 3 mm bolts.
I marked each mounting hole on the board, and made four 3 mm holes.
Size of the case bolt is 6 mm in diameter, length is around 6 cm.
Front
Side
Rear
Bottom plate
Board clearance is around 1.5 mm to 2 mm.