For my switch project, I decided to make a little pressure-sensitive pad that completes a circuit when pressed, squeezed, or stepped on. I was inspired by a book of science projects I read as a kid, which featured a similar sort of pressure pad switch made out of double sided foam tape and aluminum foil. I didn’t have any double-sided tape so I had to improvise with what I could find. I settled on a sandwich of two sheets of copper foil with a square of thick packaging foam with a hole cut in it, then wrapped the copper-foam sandwich in blue tape to hold everything together. There are a bunch of different ways to use this switch, like putting it in a chair to turn something on when you sit down, using it in front of a door to tell when someone’s there, as a compact foot switch, or as a part of a custom game controller. You could also put it in your mouth and use it as a control input by biting down on it, but I wouldn’t recommend that for many different reasons.
Update: I tested the switch with my microcontroller and it works. I reprogrammed the microcontroller so it works like a toggle switch, which is probably how you’d use it if you needed it as a lightswitch