This is a replacement rear screw clip for the BBC Micro. The screw hole is larger on one side than other, with the large hole facing outwards from the case. The smaller hole is intended for the screw to bite on the first time it's inserted. Do not be tempted to over-tighten as it won't be as strong as the original metal clip.

OnShape Model
https://cad.onshape.com/documents/05bfd6a9bbea06d181d55bd4/w/4661d94eb388a8872948a655/e/d6ceed23dfe050be8979c714

No

No

100

Recommended print orientation is on the edge, for extra strength
Set infill to 100% for extra strength. (It's thin, so will probably make minimal difference)
Do not print with rafts or supports, as it will not result in a clean enough print