2mm - I'd be concerned is too thin for anything larger than maybe 4x5 or 120 sized frames...

Upon applying pressure on some 3mm think glass over around an 8x10 area I cracked it and scratched up a neg quite nicely.

Frosted anti-flare huh ? Out of interest, what is the thinking behind that ? Even with a diffuse source like a bank of UV flouros I find that the emulsion is so close to the paper that resolution is maintained, under direct sun with its collimated nature and lower 'profile' it is ideal - I would have though any frosting would be either redundant or even harmful if you were using the sun and there wasn't enough contact pressure ...

I just use a slab of 5mm glass from the local window chaps - doesn't seem to affect exposure times under UV lights that much, 30secs in Pt/Pd for instance