Just a quick update regarding one side of the plate holder. We’ve already made the plexiglass plate ‘tray’ which is what holds the plate inside of the holder (Link). I decided that I wanted to do the door next, I made a frame to go around the plexiglass tray and the door fits perfectly. Well, I put a little extra room on the pocket of the door for whichever way I use the hinges to swing it out of the way.
This photo is a terrible and suddenly condensated cell phone shot, if you look carefully you’ll see the frame on the left with a lip around the inside edge. The door on the right has a recess to take this edge. When painted flat black (and possibly fitted with felt somewhere around the door) it should be pretty light-proof. The door itself needs a leaf spring cut that will apply pressure to the back of the plate. That will be a milled piece of aluminum sheet screwed to the inside back of the door.
As these are only prototypes, in the future I will change the thickness of the door, the thickness of the frame and instead of a large piece of plexiglass the size of the holder, I will put a lip inside the frame to take plexiglass inserts. Quarter plate, sixth, ninth and custom sizes. This will also make it easier to attach my hinges with screws.