First off you need to find some stuff to build the hand out of. There are many things that you can use, Like PVC, Coat hangers, Thick wires, and so on! Then you will need to think about what to cover it with. Things like monster mud, latex.
I will start out with the simple one first, new pictures coming soon Get a few coat hangers and cut the hooks off, then bend the flat. Then take a foot long piece of pvc and hot glue the wire fingers in to one end of the pipe, and add DUCK TAPE to the fingers and back of hands. This will help the foam stay on, If you do not use the tape the foam will just fall off and you will have a big mess!!!!!!!
It don't look like much now but it will when you are done. At this point add the foam to the hand, Take your time the foam will shoot out of the can really fast if you are not careful. Do a little at a time let it set up a little you don't want to put to much at one time.
Once you are happy with the shape you can give it a coat of monster mud
If you use mm in time the mm will crack when the foam expands, but that's ok because this will add to the F/x of the piece.
Once you are done and the piece is dry, you can start to paint it the color of your choice. You can air brush it , & use a dry brush.
you really want to go all out you can carve a hand out of 2" pink
foam like I did here. It is alot harder to do this this way but it will
make your prop stand out.
can also make wire hands covered with masking tape ans give it a
good coat of latex this works well! I will have more pictures
as I go along.