Make your circuit!
Really, you can use any bits you have that move and light up. Experiment!
Here's what we did: Power--Sound Trigger--Servo--Fan--Wire--Pulse--Long LEDx3. We fixed servo to a cutting board with a glue dot, cut a straw to fit over the servo arm, and taped the straw in place. Then we taped the 3 long LEDs to the straw, so they would wave back and forth. We also made sure to bend the end of the long LEDs so that they were in different planes of motion from each other. After experimenting, we set pulse to the fastest speed because it looked the coolest.
For the fan, we put a glue dot on the blade and then fixed an LED bike light we had around the house to the fan. (We tried using a wired littleBits LED first, but the fan wouldn't spin, surprise surprise)
Paint with light!
Set your DSLR (or shutter speed app) to have a long shutter speed--we used 2 seconds. Find a dark room and set up your bits. Turn out the lights, make a noise to turn on your circuit, and then take some pictures! We waved the fan around to make different shapes, with the long LEDs in the background. Look at your pictures and adjust your setup if necessary to get the coolest results. The end!