In April 2022, I did a silly thing, which was to attempt to make my own RGB splitter cable, with an RGB plug at each end, connecting together to a third RGB plug in the middle joining the two parts together. This was so that I could share the monitor I use with Stations 1 and 128 without always having to unplug the cable from the one to put in the other. It was a bad idea, as the cable ended up powering the machine which wasn't switched on, and if I wasn't careful, I could have ended up damaging one or both of the Beebs!
A very kind chap called Derek had already designed an RGB switch box for multiple computers to be connected to a single monitor, and he sent me a blank PCB and kit of parts so I could assemble my own. Please click on the picture links above to learn more.