Buffalo Arms sells several different types of wad punches that already have the proper diameter:
I previously posted about making waxboard wads with the wad punches that I ordered with my Triple P Loader. The thinner wad material leaves more room in the chamber for loading extra powder and conicals.
And Smokin_Gun previously mentioned that he was using his Triple P to punch out wads from egg cartons which is a thick paperboard. So now I've been saving up some of that material too. When the material is "free" it helps to defray the cost of buying the more expensive punches.
See photos post #18:
At $18 per 1000, the Cabela's vegetable fiber wads are also relatively economical and come in two thicknesses.