A lightweight (16½ gram) "helicopter" propeller launcher toy with modifications to make it suitable for my two-year-old:

• Feeder added on handle to guide the “key stick” into it
• Key stick is longer
• Key stick has a stopper to avoid overfeeding, because if overfed, the child tends to grip the propeller as well as the key

To help kids use it, use a black marker to add an arrow on the top side of the key (teeth must face rightward) and under the feeder.

Adults can launch it up to about 20 feet high.