Recently, at Solheim Lab, we sent a 3D printed mold printed in hydroperm off to Dave Feathers at Port Townsend Foundry. The mold was placed in a greensand jacket and then poured in aluminum bronze. The mold was not pre-heated, nor was it baked prior to pouring to push off all the moisture. In spite of this, the results were quite impressive. Head over to rpsculpt for more pics and info.