Our 3-year old grandson has an intense interest in understanding how things work. He shows more interest in household appliances than he does children's toys. My wife and I recently spent a week with our daughter, her husband and our grandson. I thought it might be fun to have a "gear of the day" and present the little guy with a new device every day. I located all of the following on Thingiverse and printed them on my 3D printer. Credit for the creation of these is as follows:
Gear Trio - ThreeHamsWillKillHim
Nautilus Gears - MishaT
Fidget Bolts (I added an extra component to make this more robust) - LarkysPrints
Gear Toy - deltamodulator
Elliptical Gears - cohlwiler
Geneva Wheel - PrintTo3D
Square Gears - zefram
Planetary Gears (I added the removable rods so a child could turn the gears more easily) - engrenage planétaire
