I second Bruce Newman's request for a good source for rubberized cotton
pneumatic cloth.  I had to return recent material from my supplier(s).
In addition to the pin holes I am finding that within a year of use
the creases at the open end on the pneumatics are leaking.  I am
putting larger felt punchings into each of them to prevent any creasing
during assembly.

Any suggestions, or am I on my way to synthetic materials as well?

Joel Cluskey