When I first started I got the cheap wally world tin foil. So thin you can almost read though it. Would use a piece every time I put bullets on the sheet metal. Tore if you looked at it wrong.
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Got the wild hair to try it crumpled. Mashed it into a ball, then spread it back out and covered the sheet metal tray. Using DT method. Placed the bullets on it and after the bake process would let it cool a bit and they just rolled off the foil. Almost like it doesn't stick at all.
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If you try with the bullets too hot it will tear so have to wait till they cool a bit. I'm going to use my hf temperature gun to see what a good temp is to remove the bullets.