Cold casting for model engineering, using metal fillers. What would be the best resin for this?

I would like to make castings for flywheels for example, 4 - 6 in diameter.

I tried to cast a 2 inch cube filled with iron powder but it got very hot melting the plastic mould.

Any thoughts?

Alexanm

thats a large cube to do in one time? mostly when you want to cast "big" objects you have to do it in small layers (max 1cm at the time)