The multigun
This is my kid's multigun. We made it with some scrap wood, a marble, a broken garden sprayer (thoroughly cleaned) and mini mag light, and the most important inclusion, an 8 bit DIP switch
The 8 bit switch has 256 combinations and the kids have learned to use binary in order to list all the different ray settings. They each get turns to come up with new settings and then write out the 8 bit number in binary on the multigun setting sheet. I feel like I've scored some points with this one.
0000 0001 Stink ray
0000 0010 Freeze ray
0000 0011 Invisibility Ray
0000 0100 Sleep ray
etc