4x6 Useless Machine
The 'big' project I took to maker central was this 4x6 useless machine. I had originally intended to make a 5x5 machine and have a wall of switches to flip but the dimensions of a single sheet of poplar (800x600) made it far more practical to have this arrangement. Twenty four mechanisms were soldered and wired together using a shared battery pack (2xAA) for the whole thing. Each switch has it's own arm so they can all operate at once. There were so many switches I had to draft some helpers in to demonstrate it.
The mechanism is fairly well established now with a simple PCB to solder and hold all the parts in the right places but I'm still pleased with how easily and well it came together. Towards the end of the day when the batteries were wearing out slightly it was possible to flip two switches at the same time and only one of the motors would have the momentum to turn itself off again, but apart from that there were no significant issues with it all day.
I don't think I've ever talked about the hinge mechanism on this box which makes the whole unit possible. The sides of the box protrude up through the top surface of the box and form the hinges for the flap. Two 3mm pins on either side of the flap hold the flap in place and allow it to rotate freely. The sides of the box overlap into the hole slightly which prevents the flap from falling back through the hole and allows it to rest in a closed position.
I did manage to snag the living hinge section packing up from the exhibition and it cracked slightly, I glued it as soon as I got home and it was barely noticeable, I'm just pleased it happened after.