Summary

Because the Dell optiplex 3000 micro is such a small computer I decided to mount it underneath a desk.

This mount might also fit other computers as long a they are roughly the same size:
Width: 18.5 cm
Depth: 18 cm
Height: 4 cm

Because there are ridges on all sides except the top, the computer can't be removed without unscrewing the bracket.

The pegs are not structural. They're only for making the mounting easier, so you can do without them.

You need to print 2 of each. Both can be printed without support. Just rotate the bracket counterclockwise by about 56 degrees and drop it on the buildplate.

You'll need 4 4mm screws.