How to Build Your Own Motion Activated Coffin for Halloween

Nothing adds life, um death to a Halloween haunt like animated props. More specifically coffins with lids that open by themselves. A couple of years ago I participated in building an entire haunted house from scratch. One of my favorite props was the animated coffin with the escaping skeleton. We didn’t have a lot of money to spend or any idea how to make an animated coffin so I brought my husband, the engineer, in on the project and this is the plan he devised for us. Here’s how we made our motion activated coffin.

Building a Coffin
Supplies You’ll Need
3 – 1 inch 4’X8′ sheets of plywood or scrap wood you have in the garage
1 – 1 inch 4’X4′ sheet of plywood or scrap wood
16 – small “L” brackets
32 – 1/2 inch wood screws
3 – 1″X4′ pieces of wood
4 cabinet hinges

Instructions
On one piece of 4’X8′ piece of plywood draw the outlined shape of your coffin bottom. A coffin that is narrow at the top, widens out and then narrows again at the feet is called a Toe Pincher. Use a saw and cut out the bottom piece. Trace the bottom piece on one of the other sheets of plywood and cut.

Cut one of the 3 bottom pieces you just made and cut it down the middle vertically so that you have two halves. These will be the sides of your coffin.

Now take your two side pieces (the piece you cut in half) and draw a line straight across the widest point horizontally. Cut both pieces on that line so that now you should have 4 side pieces.

You should now have one bottom piece, one top piece, four side pieces, one top end and one bottom end piece.

Use woodscrews to mount “L” brackets in all the corners and around the edges of the inside bottom to connect the sides to the bottom of the coffin.

Mount the coffin lid with the cabinet hinges and you are ready to make this baby motion detected and animated.

Making your Coffin Animated
Supplies You’ll Need
1 lawn sprinkler valve
1 pneumatic spring screen door kit
1 PIR Sensor Module motion sensor from Radio Shack for $10
12 inches of plastic tubing to connect sprinkler valve to screen door spring

Instructions
Follow the instructions on the package to mount the pneumatic spring screen door kit to your coffin. You will have to make adjustments according to whether or not you built a toe pinch coffin or standard rectangle casket.

Once you have the pneumatic spring in place connect the sprinkler valve to the spring with the plastic tubing. You can mount the valve to the inside of the coffin with duct tape or just leave it lying on the bottom.

Connect the PIR Sensor Module motion sensor to the sprinkler valve by splicing them together according to the wiring diagrams that are included in the instruction booklet for the senor module. It’s pretty basic, you just connect a couple of wires and you’re good to go.

Put fresh batteries in your motion sensor. If your battery pack is wired to your motion sensor then you will need to be careful with the wires and wrap them in electrical tape or conduit.

Place the motion sensor about 5 feet away from the coffin. Placing the coffin next to a shrub or other Halloween prop is a good way to keep the wires from getting tripped on. The reason you want your motion sensor a few feet away from the coffin is so that by the time the person is actually in front of the coffin the sprinkler valve has had enough time to send air to the pneumatic screen door spring and the lid will lift at just the right moment.

If you really want to spook up your motion activated coffin, shove a mummy or skeleton inside, add some ground fog by building your own fog machine and fog chiller and put them in your coffin. Throw in a couple of colored strobe lights and eerie sounds and you’ll have the scariest coffin in town.

There you have it. An easy and relatively cheap way scare the kiddies. Happy Haunting!