One thing for sure, I will have used a lot of M2 taps & dies, these are really brittle! And when they do break it is very difficult to take them out without damaging the part you are working on. I know where to find good quality taps & dies, but they are expensive.
I finished working on the last details.
I cut the pressure plate from 3mm thick brown Plexiglass (I would have used black if I had some). The legs of the pressure plate are 0.2mm higher than the plate, so that the film can slide without scratching.
I also finished the two locking screws. It is harder than it looks, because the mobile part is 2.5mm thick and it is attached through a 1mm axis. Just imagine, drilling 1mm holes in stainless steel!
These are not quick-release locks, but rather disguised butterfly screws
The pressure plate in place: two pieces of foam act like a spring – by any means this is sufficient since there almost no room between the back of the pressure plate & the camera body.
I also added a foam light seal at the bottom of the top plate.
Bottom view with the locking screws in position: