This is a very simple project which could be used for an infinite number of different purposes! You could use your pressure plate switch to add perfect timing into your haunted house, automatically trigger your doorbell when someone stands on your doormat, track the presence of mail or parcels, or even set up your alarm clock to only turn off when you get out of bed and step on the switch! The switch is made up of two separated sheets of aluminium covered cardboard which connect when pressure is applied, closing the circuit.
The possibilities are really limited to your imagination. This project allows you to easily build something that is impressive and useful! The best thing about this project is that all you need to get started is some wire, aluminium foil and cardboard! To begin making your own pressure plate check out the following instructable from Jason.