You could experiment with printing wax to make your shape, then encase the wax in potter's clay, forming access pipes to allow molten metal to enter. After the clay has dried, just pour in molten metal and the wax melts and the void is filled with metal. Very ancient way of making metal castings. But you only get one end product per mold.

If you liked, you could fire the clay with the wax in it before using the mold. The wax would be gone before you poured the metal, so you only need one pipe into the mold chamber.

OME