I know this was one of the harder things to find and figure out. You can do several things. Buy wadding from the Gun store which is about $7.50+ for 100. Or you can buy 1000 wads for $12+ Shipping from Dan App. Great guy has good prices. This is the easiest way to go.
OR you can buy a 7/16 Arch Punch. You can find them on Ebay for about $8 plus shipping. Make as many as you need.