4mm hole transmitter box

It's a remix of the 6mnm hole version. Since I decided to go with the overall 4mm magnet version and didn't want to order 6mm just for this part, I remixed it to take 4mm magnets, knowing fairly well, that the magnetic force won't be as strong.

The original part uses 6mm magnet but since I git some leftover 4mm ones I thought of just remixing it quickly.