This is a mount for the Brother P-Touch D610BT
It uses the small threads of the multiboard and I suggest the 13 mm Small Thread, Plain Head, Shank T-Bolt to fix it to the board.
This one can be printed using the back side directly on the bed without support (as shown on picture).
Also included separately is a sidecar that will try to catch the labels. It mostly works, design could be improved. It's easy to just pop a new module on the side using the 2 pegs. The side car needs support to print.
You insert the device either by pushing forward on it, there is a bit of resistance because of the left side clip. but the clip will bend and pop into place.
It's also easier to insert it from the right side to left while pushing on it. It's easier and the clip doesn't need to bend.