Kids generally can be amused pretty easily, but when jangling keys stop holding their interest you might want to take a look at [drenehtsral]’s new project. He’s created an automatic bubble robot (YouTube link) that keeps the kids endlessly entertained!
The project started as an idea at a festival where one of [drenehtsral]’s kids took great interest at a bubble machine. [drenehtsral] had never heard of a bubble machine before, but it turns out that it’s pretty simple in practice. All that’s required is a tank of soapy water, a motor to turn the bubble wands, and a fan to form the bubbles and make them waft gently through the air.
[drenehtsral] also used a 12V battery for power, some other hardware to hold it all together, and a 5V regulator and some other control electronics for the fan and the motor. He notes that he could have bought a bubble machine but in true hacker style found it fun to build himself. The next step in this project could be something to vary the size of the bubbles, or perhaps a set of wheels for the robot so it can entertain the kids on the move!