BBC Micro keyboard hole plug.

When restoring vintage BBC Microcomputers the perforated area on the keyboard originally intended for the speech expansion ROM cartridge is often damaged and repaired with messy tape. This 'thing' plugs neatly into the hole significantly improving the look of the machine.

The fit is quite snug, I intended to apply hot glue to the rear but didn't find this necessary in practice. However if you need to defeat small prying fingers you might.

There is a cut out in the plug section. That needs to be aligned with the speaker as that can intrude into the space where the plug goes.

I designed, and I us the word advisedly, this in FreeCad so have include those files in case you want to improve on it.