How to Make a Fake Arm Cast

A realistic and reusable plaster arm cast can be constructed for theatre productions from materials found around the shop and at hardware and medical supply stores. A little careful engineering is needed to build the cast so it will go on and come off the actor quickly and yet reliably remain on the arm during the entire scene or during action sequences.

Prepare to make a cast on the actor’s arm. Cover the arm with petroleum jelly. Slip a cotton knee-high tube sock over the arm. Cut off the toe if necessary.

Dip plaster-impregnated bandage strips into warm water. Let the bandages soak for approximately one minute. Wring out excess water. Wrap the bandages around the arm, just as if building a real arm cast. Make sure the bandages are not wrapped too tightly however: there should be enough room between the bandage and the actor’s arm to insert a thick finger up the “sleeve” of the bandage. Do not build a cast up the arm above the bend of the elbow. Continue adding bandages until they form a shell no more than ¼ inch thick. Do not wrap the bandages around the hand or fingers. Do not allow this shell to dry completely.

Cut the cast open. When the bandages have set to a not quite hard state, slide the under-stocking off the arm while holding the cast in position on the arm. Insert seamstress shears, with the tips covered with duct tape, into the wrist end of the cast. Slowly cut the cast open. Make only one long cut. Gently pry the halves of the cast open enough for the actor to withdraw his arm.

Stuff the empty cast with newspaper. Build up the outer surface of the cast with more plaster bandages until the cast is about 1 inch thick. Do not bandage over the cut. Let dry overnight.

Slip a rubber glove over the actor’s hand. Make a loose plaster bandage cast around the hand, leaving the fingers and the thumb free. Keep the opening wide around the wrist. When dry to the touch, slip this plaster glove off the actor and let dry.

Smooth any rough edges with wet plaster bandages so they won’t chafe the actor. Prime and seal both casts with flat white latex paint and let them dry.

Slip a white tube-sock (with the toe cut off) over the actor’s arm. Pry the cast apart widely enough that the actor can slip his arm into the cast along the seam. Attach long strips of heavy-duty white Velcro along the top edge of the cut seam, toothed side down, and another strip of Velcro, with the fuzzy side up, on the other side of the seam. Close the seam with the Velcro. Slip the cast glove over the actor’s hand and connect this glove to the cast at the wrist using bands of white matte-finish cloth gaffer’s tape.