John,
I'm not freezing at all - I've seriously sprained my knee, fanfares go here

Just sitting home far away from my newly-acquired half-broken in post Toyo-Omegaview 45D
An idea with surface planer is okay, while you've got one, and made your pressure plate from the wood hard enough... if it gives no scratches, it's OK

And the guiding pins can be made from brass rod, or be just wooden - what's more attractive to your design

They'll keep the film in place, and prevent the plate from swinging on elastic hinge.
There's a simple way to turn your appliance to continuous-cutting machine - just make a delimiting "stop ruler" for the film side opposed to knife, maybe from a piece of metal angle, sliding on your existing screw-nailed delimiter, and entering a narrow dedicated slot in the base board. You have to raise the delimiter the way it would allow the newly cut sheet to escape to the left of roll. You put the delimiter over this hole - adjust film and put down the pressure plate - cut - raise the delimiter, and push the film sheet to left - lower the delimiter - adjust - etc. Maybe that's faster?
Oh, and you may also add a small rack for your roll over the whole thing, so the dusty box won't be needed...
Cheers from cold cold Moscow,
Zhenya
John Bartley said:
Zhenya

- I hope you're not freezing to death in your new lab. Remember, lots of potato juice to keep the flu away eh?

I thought of putting a pad under the pressure plate, but instead what I did was run the plate (which is wood) through my surface planer to get a glass smooth surface. In the 5 dozen negatives that I have cut so far, I have not yet had a single scratch. This film is tough, tough, tough. I do like your idea about the pins though, not necessarily just as film guides, but also as pressure plate guides. I may just do that this weekend ....