While it's very difficult to make the skin on a fake human hand look realistic, a rotting zombie hand can be fashioned out of household items and a couple of inexpensive items from the hardware store. A DIY zombie arm with the hand attached makes a great prop for Halloween costumes, horror videos and zombie walks, or plant one in your front yard to bring the zombie invasion home.
Bend the wire (make sure you get pliable aluminium wire, not stiff wire) into the shape of your hand, twisting the wires together to make the fingers.
Wrap the ends if the wire around the two 12-inch dowels, to suggest arm bones. Hot glue the wire to the dowels.
Dilute 1 part white glue with 1 part water. Tear newspaper into small strips.
Dip the strips of newspaper into the diluted glue. Lay it over your wire and dowels, building up a ragged-looking hand. Leave some of the wire and wood exposed. Once you're finished with the papier-mache, rub dirt into it and allow it to dry overnight.
Paint the hand and arm as desired, using grey, brown, tan and red paint. Don't worry about the paint getting mixed in with the dirt; it's part of the effect. Allow it to dry overnight.
Cut the sleeve from an old shirt. Rub it in the dirt and give it a couple of tears with the scissors. Put the sleeve on the arm. Hot glue the fabric to the dowel in a couple of spots to keep it from falling off.
To create a zombie arm reaching out of the ground, stick the bottom of the dowels into the ground, using rocks or dirt to prop it up.