I purchased a roll of zinc flashing to solve a moss problem on my chicken coop roof (which worked fantastically just as advertised) and I had a lot of material left over. It looked to be about the same thickness as Hornady checks, so I began to use this excess material instead of copper or aluminum in both my Freechex and Pat Marlin checkmakers. Thus far, I see no performance difference between copper, zinc or aluminum clecks. Although the zinc may be a bit thicker, it's soft and seems to seat firmer on bullet bases than aluminum checks, and sizes down in the dies just fine.
https://www.lowes.com/pd/Constructio...specifications