You've all probably already seen the severed hand illusion as featured here. It is done by using an apparatus which simulates a black leather glove that wraps around your wrist. It's attached to a fake, bloodied, stump-of-a-wrist. This is revealed in the illustration shown below.
Although this is very effective, you can enhance the effect by applying some dead-looking make-up to your hand. Painting liquid latex onto your hand can give it a decayed look. Consult any of the monster make-up books currently available for help with this make-up effect.
Why not create a new dimension to the effect by adding a puppet to the ''severed'' hand. A snake-head puppet could be very effective by using your hand to work its mouth. The snake's body could be attached to the other side of the glove. A nasty rat puppet could also terrify your guests.
You should use old style work gloves to ''handle'' these animals. It will add a more realistic effect than black leather gloves. Twisting and curling the snake's body with your free hand will make it look as if it is trying to get loose. The operator could have his hands down inside the animal's cage when the group enters. He then brings it out for their inspection. His hand will, of course, be inside the snake's head, causing the mouth to snap open and closed in a menacing manner.
The above "How-To" is an excerpt from Tim Harkleroad's "The Complete Haunted House Book" for more information about this and other great haunted house reference books go to MoonLighting Publication's website "Haunted House Books On-Line" at www.hauntedhousebooks.com. You can e-mail Tim at moonpub@aol.com