If you're having trouble finding some of the components for this project, you can purchase them as a kit from my store (six colors available).
Check this project out on Make: Projects!
Step 1: Materials and Tools
wooden embroidery hoop
switch or snap
sewable battery holder
If you want to get the high quality frog template design, you may download it for free here:
Step 2: Prep work and standard embroidery
Step 3: Prepare the LEDs
If you're using a standard toggle switch, now would be a good time to solder on some leads and coil the ends. If you're using a snap, just move along.
Step 4: Sew the positive side of the circuit
Without cutting the thread, stitch a path (still in backstitch) to the other firefly, and sew the square-coiled lead the same way you did the first. Tie off the thread. Weave it back along the stitched line the same way you do with the regular floss, then cut it. The reason you weave it back is that the end tends to fray, which could cause a short circuit if it were near another conductive trace.
Step 5: Now the negative and one half of the switch
Step 6: Switch and battery holder
Step 7: Finishing up
Turn it over and flip the switch or snap the snap. The lights should come on! If they don't, turn it off and check for good connections and shorts.
Trim the fabric within 1.5 inches of the edge. Use regular thread and a running stitch to gather the edge on the back side. Here's the back. You can change the battery when it dies. If you leave it on 24/7, it should last 1-2 weeks, gradually getting dimmer as time goes on. Enjoy!