Dismantle USB webcams and turn them into digital microscopes. All it takes is a screwdriver, some glue and a couple of hours - after which you'll be examining water flies and water bears (tardigrades) close-up. Ticket price includes all kit needed for everyone to make a working microscope to take home. Please bring a computer – or at least one to share between your group.
Image by MadLab via Flickr.