A heavy yet easily cut substance?

heavy metals tend soft ad ductile not use can made of coping saws(in opinion)sculpt in wood,balsa, styrofoam or somesuch,cover sculpted object in fireclay , burn out, or dissolve pattern and' when mould clean , dry. cast lead or solder mould,when casting made clean off mould material , fettle casting.fettling means cleaning , polishing required.if sculpture has simple shape make 1 pattern , use split mould.if want low melting point dense casting try woods or printers alloy give exact reproductions , can re-used easily.

im doing little diy project , wondering if there heavy yet sculptured substances. know weight result of high density , therefore substance hard cut, if there can cut coping saw appreciate help.
in advance!

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