I agree with judy about the great hand-casting materials available, like in dick block. I think you could cast them then in resin or cement. With resin you could have inclusions or leave it transparent.
I am participating in an art exhibit based on the Stations of the
Cross. My station is "Jesus is Judged by Pontius Pilate," and I want
to do a fountain, with cast hands being "washed' by a constant stream
What would be the best way to cast actual human hands and add water to
the piece? I want detail -- skin wrinkles, etc... I am thinking of
plaster casts that are sealed somehow, but is there another medium
that might be a better choice? I would probably rig a fountain kit to
go into the piece so the water constantly pours over the hands, and
build a shrine around the hands to hide the mechanical stuff.