It's a Small World for a Minnesota Model Maker

Model maker Neal James of rural Elk River, Minn., has built 27 engines, including seven gasoline engines.

Hot air engines
A pair of hot-air engines made by Neal James. They work off the heat from the hand. He scaled down larger hot-air engines, and sells the plans for these two. The greater the temperature disparity between the hand and the air, the faster the engines turn.