This extremely detailed prototype of a motorcycle braking system from the early 1900s looks really cool. From the description it is fully functional and might have been used to demonstrate the operation of the design or maybe it was just for a display of some sort. Whatever the case, if you like nicely machined models, this is pretty neat.
This is one of several very early odds and ends on a site called Radio Guy. He also has a 1921 Evans Power Cycle plus some very weird medical, radio and scientific contraptions. Worth a few moments of browsing if you like early technical things.