I made a switch that is controlled by blowing. As shown in the schematic diagram, the two metal plates of the switch are connected with opposite sides of the LEDs.

Normally, when the metal cylinder is connected to both of the metal plates, it creates a short circuit between the LEDs and so the LEDs are off. If I blow the metal cylinder away from the metal plates, electricity has to flow through the LEDs and they are on.

To make such a switch, I prepared two L-brackets, two wires with their ends stripped, a piece of cardboard and a piece of paper.

Then tie the wires to the L-brackets and cut the cardboard into rectangles.

Make them into a box…

Cover the box with paper to make it less ugly.

Finally, put the cylinder into the box and connect the switch to the circuit.

Here is the result—Blow it hard!