Special effects artists create realistic body parts for films all the time. Many of these parts are actually made of ballistic gelatin, which forensic scientists also use to simulate human flesh when they are studying wounds. These gelatin parts are made in moulds, which are usually cast from live models. This means that you can make your very own realistic body parts at home, even if you have very few artistic skills. You just need to find supplies and a willing model.
Cut a U-shaped hole at the short end of your shoebox that is large enough for your model to rest her forearm in. The bottom of the U should be 3 to 4 inches from the bottom of the box.
Line the bottom and edges of the shoebox with duct tape so that the plaster does not leak or seep through the cardboard.
Prepare your plaster of Paris as directed on the packaging and thoroughly coat your model's arm in petroleum jelly.
Fill the bottom 2 inches of the box with plaster of Paris. Have your model nestle her hand, palm side down, halfway into the plaster, with the forearm resting in the U. Wait for the plaster to set. Have the model remove the hand when the plaster is firm, before it gets hot. You should now have the bottom half of your mould.
Allow the plaster to dry completely. Cover the bottom half of the mould and the model's arm with petroleum jelly. Have the model rest her arm in exactly the same position in the mould and pour in enough plaster of Paris to cover the model's hand. Allow the plaster to set until it is firm, but not hot. Gently remove and flip the shoebox over and remove the top half of the mould. The model can remove her arm. Allow the plaster to dry.
Outline the hand indentation in the bottom half of your mould with latex caulk and fit the top half of the mould back onto the bottom half. Make sure that the caulk forms a tight seal and set the mould on a flat surface with the fingers pointed down. Wrap duct tape around the mould so that it stays sealed together. Allow the caulk to dry.
Prepare your ballistics gel as directed on the package and pour into the mould through the opening where your model's forearm was. Allow the ballistics gel to dry completely. If you pull the mould apart very gently, you can use it multiple times. If you need to, though, break the mould to reveal your realistic fake hand.
Paint the fake hand with flesh- and wound-coloured latex paint to make it look more real.
You can buy ballistic gel online or save money by making your own. You can create other realistic body parts if you use a bigger box to make your mould in.