Some can do this process in a small cup. One fills the cup with photopolymer , drop some polymer on it , these drops flowed and expanded in the cup and uv beam shot. You have a hard mold and soft core , remove the unset polymer from the set photopolymer and fill the gap with low temperature melt high percentage tin , low perc. copper and when the metal set , put everything in to acid bath , photopolymer melt and your fluid free form part remains.
All opposite could be done also.