Have You considered getting a 3D printer
There has been a bit of a pause on this thread. There is an openscad file by buffcleb on Thingiverse for an index plate that is fully configuarble for size and hole patterns, even mountings. Just had to have a play with it. I didn't want to try out a 5 hour print for a proper plate but then thought the best way to make a specific prime is often to start with that number - rather self defeating though in the old days. However a single row could be printed rathe more simply (hour and a half). As an experiment I have printed a 73 hole plate quite thin that could be mounted on an aluminium carrie...