Similar to using washers, during casting, you pour a little hydrostone, plaster, whatever into the mold, and then the slug, then more hydrostone. As it dries and settles you are left with a mettle slug inside your plaster that you can pick up with a magnet or have it adhere to a magnetic surface. This way you don't have to worry about polarity. It's an idea I have been playing with for a while but have yet to really use it for mass production.
Molds: 18, 46, 59, 70, 71, 72, 73, 82, 85, 202, 205, 264, 266, 281, 282
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