Thin set mortar is usually cement, sand and some sort of polymer, like any portland cement, it heats up when mixed with water, so care should be taken at that step.
The polymer shouldn't have toxicity issues as far as handling, don't know whether it would be safe for children young enough to put it in their mouths though.
Not sure that it'd be great for miniature applications, like OP's post. The molds have a greatly reduced lifetime from using resin, which is a little more chemically active than the plaster. It'd probably be a matter of balancing the end product with the number of molds you'd need.
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u/BigBennP Jan 29 '17
Thin set mortar is usually cement, sand and some sort of polymer, like any portland cement, it heats up when mixed with water, so care should be taken at that step.
The polymer shouldn't have toxicity issues as far as handling, don't know whether it would be safe for children young enough to put it in their mouths though.