Considering the background of you folks, a material that provides the starting point for investment casting should come to mind. Wax for sculptors was suggested in one of your forum’s posts. There’s sure to be other materials that serve this purpose. Here’s a WIKI article on investment casting.
I had to print a project for a friend in PLA, which would be used in a lost-wax casting process.
He needed to have more delicate details so he finally went for printing in SLA. (on a Stratasys-Objet dimension machine)
If the material will go away in the process anyway, I don’t see a reason why not to use PLA. It gives great details, and is already widely supported in the 3DP community.
Tough, 3D printing in wax can be used in some very specific cases, and if one wants to be able to recycle the material the same way with all the other lost-wax casting in the foundry.