Draft: Break-out supports for the long bridges over the cut-outs in the microscope stand

The microscope stand has large cut-outs for the electronics drawer. The top of each cut-out is a long bridge that is prone to sagging. The sagging makes it harder to insert the electronics drawer (#292 (closed)) and is unsightly.

This MR proposes break-out sections in the cut-outs to support the bridges across the top of the holes.

This is entirely untested!