When I was a kid I get a plastic set that was empty inside, to made it gain weith I filled it up with clay and marbles.
The idea is to have something inside and something heavier at the base.
If I was to do it againg must certanly will use rocks instead marbles. If I want to go fancy will use magnets and have a magnetic set. Electronic stores carry this magnets things.
The proyect you describe sounds like you want to buy a lead plate and cut the circular coins costume zise to the pices, if this is what you mean then you need some tooling too.
I was just wondering if I can buy weights for my own chess pieces and somehow put them into a spare chess set that I have. I got this idea from a friend who got his weighted chess pieces from his coach who made them himself.
I have heard that you need to buy some lead and then cut in and then glue it in so does anybody know where I can buy that or have a tutorial about how to do it.