Central in my design is a square tube that is just big enough to let a magnet roll through. Tubes like this one are used to direct electrical wiring in a home and should be available in any hardware store. In the picture you see it in the top. Beneath that you see the
neodym magnets, really tough little magnets that jump together from quite a distance (up to 10 cm/4 inches). The material itself that I use to build is styrofoam board that should be available from any hobby/model store. It’s 5 mm thick and rather tough, and it weighs next to nothing.
