Here is an old school project — using no electronics — but still a cool build in many ways. I suppose you could add some electronic bells and whistles to make it even cooler, but it is a great idea and a great build for when you want something retro, interesting and cool!
I was asked by my wife to create a "contraption" to help sell tickets [all proceeds to charity] for her book launch at the local independent bookseller. Since the novel is set in 1880 New York, I wanted to create a Victorian feel and opted for a true, gear-clanking coin mech over a electronic version. I Borrowed/stole heavily from this piece for the guts of the device. The overall feel had to be Victorian and inform the users about the launch. I had a great time doing this and learned a lot about gearing, brass and a method for affixing paper to wood that I will be employing from now on.