Great explanation. Yes - I’ve done this before! Built up a system with a RAID array but then realized I wanted a different boot drive. Didn’t really want to wait for dual 15Tb arrays to rebuild - and luckily for me, I didn’t have to! Because the metadata is saved on the discs themselves. If I had to guess (I could be wrong though) - I believe ‘sudo mdadm —scan —examine’ should probably bring up some info about the discs, or something similar to that command.
Just note that if you 3D print something, if you use the wrong material, there’s a chance it may melt.