So since when is 3D another word for Thread? Pretty sure it means 3 Dimensions lol.
Molds do accept Liquids, but the Crucible doesn’t allow Liquids to be extracted from it due to the Temperature differences, that’s why for automation of Alloys and such that happen to have Fluids a Smelter and a Mixer are recommended, which then output via Pipe into a Mold. Molds do accept Fluids, Crucibles do too but that doesn’t make sense to pour already molten stuff into a Crucible.