The bottom of the bantam case is made from two pieces of the old AT case's side.

These pieces are held together by drilling and tapping for four # 6 - 32 screws (common computer screws).

Screws were ground off on the business side.

Then holes were tapped to accept screws that will fasten the motherboard in place.

I wanted to keep the 'stand offs' as short as possible (3/16") but it was obvious that even a gentle squeeze would cause the metal of the case to kiss the electronic underbelly of the motherboard. I just knew that was a bad thing. So I sacrificed the plastic lid from a Tupperware container to insulate against that possibility.

There were a few plastic mounting lugs and thingies sticking out of the bottom of the board that measured 1/8" or so. Cutouts had to be made in the plastic to allow for them. The stand offs are moderately hard rubber cut from old computer feet.