Back when I needed to use filler because all the 16ga wads that were available were all made for at least 1 oz loads, if not 1 /8, I had a tool with which I cut discs out of the styrofoam trays that come with meat, etc. Worked well. Then we started playing with cereal. I used Quaker Puffed Wheat or Puffed rice. Did the job just fine. I'm about to start using Gulandi SG-16 wads to reload 7/8 oz. Expect I may need to play with cereal once again. I already have Cheerios on hand.