https://www.asymplex.xyz/ has unique keycaps

Congratulations! Time to add a MMU to it ;)

If you like to tinker but don’t want (and don’t have the time) to build something like the ERCF or Tradrack, I would suggest looking at the 3MS. It is a DIY solution consisting of a stepper and extruder per filament (you can re-use an old mk8 extruder if you have one) and a splitter.

Oh thinking of the questions’ context: For the handwired builds I use 3d printed hotswap sockets and keep all parts reusable.

Two hotswap boards, then switched to handwiring and designing cases - much more fun.