Dug this up from a previous post of mine for register pin/punch DIY: I would try the easiest(I think) get hold of 2 of these office punches, they don't need to be new but of the same make... https://discountoffice.be/p/perforator-leitz-5180-inleg-64mm-zilver/ Keep one to punch your negs and papers, the other strip out one of the punches and cut it down to about 4-5mm height 2 bits(obviously) and punch a very thin strip of flexible plastic/metal on the working punch. and glue these bits into the strip. Now you have a punch system. The strip can be taped or glued to your contact frame making sure the pins go into a recess in the wood side of the contact frame or the glass will break. Just a thought, you might not need two punches just take one of the intended sheet binders an cut the bits from the ring clips in the binder(normally 2 in there).