Here's something I made a few years ago for a Cub Scout Halloween Party. The kids enter a dimly lit room and sit in a semi-circle around a small table that has a old box supposedly found in the Egyptian sands near the temple of Isis on it. Three rope strands hang from the ceiling ending in hooks just approximately a foot above the table. Egyptian / middle Eastern music plays softly in the background. Ushers dressed in Egyptian cothing stand quietly near the table as if to portray security around the box.
Enter in the Egytian Priest wearing full Egyptian garb, carrying a tablet high above his head, murmuring some mumbo jumbo as he walks to the front of the table.
A story is told about how the hieroglyphics speak of a boy that was accused of stealing. The Pharoh tells the boy that if he tells the truth about stealing food he will set him free but if he tells a lie, he will cut off his hand. During the trial the boy is adamant that he did not steal the loaf of bread, but is later proven that several witnesses testify he did indeed steal it. So, off with his hand and it was then cast into the desert to never be seen again. NOW... thousands of years later, the hand is discovered near the tablet and the spirit of the boy is to now forever tell the truth when placed upon the turth tablet of Isis. Because as the inscription states, no one can lie when in the presence of Isis for the Eye of Isis "sees all truth."
At this time, the stone is then connected to the ropes, resulting in the tablet hanging suspended about a foot off the table. The Priest calls on the spirit of the boy, to help set an example for the young children in the room, the value of telling the truth. The priest after walking the box with the hand around the room to show the children a hand is in the box, then removes it from the box and places the hand on the suspended tablet.
During the show the Spirit of the Hand is asked questions that can only be factual and be answered with either a yes or no answer. Two taps of the index finger indicates a yes. A single tap indicates a "no." An Egytian like sign showing this is an added prop to help the audience remember that two taps = a yes, one = a no.
The show starts with well known aswers like "Is the president of the USA Barack Obama? two taps suddenly occur by the hand on the tablet. Soon, the kids are fixated on the hand. After several questions are asked proving the Spirit is correct, prediction type questions can evolve and the sky is the limit how much prediction / scary answers the audience can handle. Finally, the priest begins to sense the prescence of the boy is drifting away and askes the boy if this is the last question, then of course the answer is yes and the hand no longer responds.
Here is what you need to make the Spirit hand:
1. Door bell - the type with a real bell with a hammer striker that physically uses an electromagent to move the hammer to strike the bell.
2. A transformer to drive the electromagnet from 120 VAC.
3. A momentary pushbutton to complete the circuit to drive the electromagnet when pressed.
4. MDF for the stone.
5. Sculpture wire, plaster of paris, cheesecloth, and paint
6. electrical wire
1. Tear apart the bell to get at the electromagnet. Measure the height of the magnet to the pole ends to determine the thickness of the stone that will be needed to conceal it. one pole will protrude out the top of the stone to pull down the finger of the hand.
2. Cut the MDF into the pieces required to laminate for the thickness required. I only needed two triangular pieces to cover the thickness of my magnet.
3. Route the underside of one piece to make a raceway for the wires to two corners and room for the electromagnet. Drill a hole for each pole of the magnet through the top piece of the MDF so that the poles protrude and hopefully flush to the top surface. My magnet had pole essencially flat to the coil so my poles are actually too low without having to reveal the coil. In a dim room, this is not seen anyway - at least by kids! Drill holes in each of the two corners to acceptthe bolt and wire that will be installed there.
4. Hotmelt glue the coil into the top piece, and glue tack the wires in the race way to the holes in the corners of the stone.
5. Strip the ends of the wires and solder or affix it to the brass bolts that are pushed through from the top piece MDF, and long enough to attach the bottom MDF. Make this connection secure as this needs to be reliable as we glue the MDF together. I used brass to solder the wires to the threads.
Decision point... Evaluate how you can best conceal the poles of the magnet. I wanted the strongest pull possible so i left the poles exposed. I ended up with a rather weak pull even still. I got lucky in that the poles looked like the head of an aluminum roofing nail, so I placed a number of dummy nails around in a perimeter to conceal the poles. Looking back I could have drilled small dimples in the wood to match the poles and painted the poles. Either way you have to conceal the poles as best you can.
6. Glue the two halves together and nick & grind the edges and paint to look like a tablet.
Let's make the hand. Take some sculpting wire or electric fence wire and using your hand or a small child's hand as a model, bend a basic wire shape of a hand. Kind of like a basic coat hanger shape of four fingers and a thumb.
Then use it as a basic form, add more wire cross the shape to build up three dimensions. Do this for all the fingers and the thumb. A lighter gauge wire works best here. No need to build up the index finger as this gets cut off. When the wire sculpting is done, cut the index finger off and form a hook loop here the finger will pivot. Make a separate finger out of new wire and add a top loop to it and hang it on the hook. Bend the hook closed. Test the shape of the pivot on the stone and fire up the elecctromagnet. Check it the finger gets pulled down firmly. Note that the action will change once you plaster up the finger so keep it it mind adjustments are coming once formed.
Once the action of the hand and finger looks good, and hand takes final shape, coat some cheese cloth in plaster and form it over the wire frame - entire hand leaving access to the index hole and pivot loop. Do the same for the index finger. Let everything dry.
Pain the hand a decrepit color, maybe add fingernails like i did out of tongue depressors, and put a final loose layer of cheesecloth over the hand. Take care to cover the hole to the index finger area.
Make the hanging support with a scrap off the MDF. Cut a smaller triangle and screw an eyescrew into the center. Tie a rope on it or similar to hang from the ceiling, a drop in ceiling rail or similar connection. This piece also needs to be routed to help conceal the wires. Drill holes in the corners and run wire down to the hooks.
Fabricate hooks out of copper wire to make an electrical connection. I concealed the connection with jute string and hotmelt glue. Note the connectors that have the power have their backs soldered together so I can easily tell which hooks go onto the connection (front leads) of the stone. It would be embarassing if the spirit never showed up to work!!!
Finish making the electrical connections from the secondary side of the transformer through the momentary contact button. and conceal the entire electrical works up in the ceiling.
One of the Egytian guards operates the button to answer the questions.
i also attached a write up I had for another option on how to build this.