An alarm plate is a basic switch which will activate when pressed. the materials you'll need are listed below.
1. peices of plastic or wood i used wood. 2. sponge or foam 3.foil aluminum 4. A few wires. 5 a battery compartment. it is nice to use more than 3 batteries if you use the sound amplifier. 6. motor or any sound making device. 7. speakers
put the sponge and wood together. like shown.
attach foil with tape to the wood. When the foil makes contact the switch will start
get batteries with a switch. You might want to sold wires to the compartment.
now get a motor. if you don't sold the wires it might be difficult in the next step.
now attach the motors wire to the bottom foil part. Attach the positive battery wire to the top foil. Also ready the battery negative wire and make contact with that and the motor.
now after making the contact with the motor press on the wooden plate and the motor should turn on making noise. Always remember to check the foil.
you can add a sound amplifier to your pressure plate by using speakers with the motor. Or you can make it louder by putting tape on the motor. if the tape hits paper see what happens