You will need:scrap woods from the other projects. black screws for woodone strong cord (the best is metal string)duct paper and strong wire for paper.
Why:Mainly for fun but also as educational experiment. I use this well known 'battery from vegetable' experiment to show my son, that electricity can be found.
Easy to make, durable and from just 3 elements - alarm device. My son loves to set this alarm to his toys, doors to his room.