NB: I am currently precisely testing Dora Goodman Zone Z1(Mamiya Universal Press/Super 23-lenses and Graflok 23/G-backs(at least some are matching....).
I have been checking focus by comparing with MUPS23-system and using all kind of groundglasses plus rick olesons magnificient brightscreens. he could cut it to custom sizes but i fear not up to 4x5. and there are open questions.
NB 2: Zone Z1 can be advised-body is ok, a bit too short.
Gill get other groundglasses. thought about a universal one for all kind of backs.
Hope this is not offset.
Came here after surfing Satin Snow Groundglass and Hopfglass-both seem gone.