Hi,
rubber is so squishy its really hard to punch....depending on the rubber compound.

At University to cut holes in those red rubber bungs, which is near impossible, we'd drop the bung in liquid air until it was frozen solid, and then cut it with a sharp annular tool,
sort of like a hole saw. Provided you took it quietly and did not use to much force (and shatter the bung) it worked well. Biggest hurdle was to handle cyrogenically frozen parts,
its real bad for your skin!!

Craig