Gently wrap a rubber band around your battery, catching the leads. These batteries break really easily at the joint where the wires connect to the battery. This little step will add strain relief and save you a lot of heartache.
Slip the Circuit Playground Express and the battery into your t-shirt's pocket and shake it around. Watch it sparkle! On a light-colored t-shirt, or for a subtle light effect, you're done!
If you used a dark colored t-shirt like mine, you may find the lights aren't quite dramatic enough. Here's how I added the Circuit Playground Express to the outside of the pocket for a little extra oomph.
Cut a circle "moon" out of holographic sticky-back vinyl. (This is the other layer in my Cricut project) It should be slightly larger than 2" across so it covers the whole Circuit Playground.
Stick the vinyl to the front of the Circuit Playground Express to diffuse the light and create a sparkly moon.
Slip the battery in the pocket and stick the Circuit Playground Express to the outside of the pocket. Flick the moon and watch it sparkle!