The little water wheel

The small water wheel is put into the backpack before the trip and put together when taking a break at the stream. You don't need glue, because as soon as the water wheel is dipped into the water, the wood swells and the parts hold together tightly. Now it will soon be babbling in the stream between two forks of branches or on suitable stones as a bed.   Before you head home, you take the water wheel apart and let the wooden parts dry for the next trip. From 5 years.