I made the cork discs. I ended up using a roll of cork I picked up in the stationary section of menards. I found the easiest way for me was to simply make squares put them on a clamp then cut off the corners and take a file to round them off. It worked surprisingly well, was a bit tedious, but I know they fit.
Now I can get onto glueing up my old violin.
@Batto and others. Photo lends the appearance of galvanized carriage bolts. If so, extraneous protuberances on threads may slow the progress of the wing nut during glue up. To be foretold is to be forewarned.
I figured that out when I was using the wing nuts. Thats actually an extra step I omitted writing down, every clamp I ended up screwing down as tight as I could to 'break in' the threads. I'd actually argue that if you have access to a tap and die re-chasing the threads would be a benefit.
However I misplaced my set so go me!