Because of Reasons, I didn't get a picture of the finished pack until much later when the squirrels returned, and it is Low Quality, but you can get the sense of it at least.
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Step 1: Tools & Materials
- one felt battery cover (URL)
- small amount of velcro
- conductive thread
- two LEDs (I used through-hole but SMDs would work if you solder a bead to the leads, to sew through (URL))
- a pair of magnetic purse closure snaps
- EL wire (not shown in the pic)
- hand needle
- round nose pliers (the kind where each prong is round)
- needle nose pliers (the kind where both prongs together, when closed, are round)
- hot glue gun
- sewing machine
Step 2: LED Eye Circuit Setup
First determine the positive and negative leads on the LED. You can tell in several ways. Unless you have a very SPECIAL kind of LED, it will have a flat spot on the bottom of the casing, by the negative lead. The interior of the LED has two shaped bits of metal, one larger than the other; the larger bit is connected to the negative lead. There's a good picture of it here. If you are in doubt, take one of the coin cell batteries and hold it between the LED's legs. If it goes on, you have found the positive and negative legs (positive leg is touching the battery's positive side, negative the other). If it doesn't go on, it's the other way around (or possibly the battery or LED is dead).
Using the needle nose pliers, roll each leg of the two LEDs into a spiral next to the base, as shown in the picture. This will allow you to sew it down flat. Thread a needle with about 12-15 inches of conductive thread. You won't use all of this on the initial segments, but will use it later.
Step 3: LED Placement and Stitching
Now do the same thing with the positive traces, starting with the left-hand LED and sewing to the right-hand one, so the long tail remains on the right side of the work as in the third pic.
Tip for sewing the "traces": get the conductive thread embedded under the fabric as much as possible, to minimize the possibility of short circuits.
Step 4: Tongue and Negative Trace
Sew the negative trace (on the left side) through the tongue fabric, out to the end of the tongue where you will place one side of the magnetic snap switch. Each side of the switch consists of two parts, a snap part and a backing part. The snap part has two flat legs sticking out the back, and the backing part has two slots through which they fit. Push the snap part legs through from the front of the tongue to the back, snipping the fabric slightly if you need to (but you may not need to). Place the backing part over the legs, from the back, as in the 8th pic. On the front side, wrap the end of the conductive thread around the legs of the snap, under the snap part, several times, as shown in the 9th pic. Pull it tight enough that all the wraps are hidden under the snap. Then bend the legs of the snap down from behind using pliers to hold it firmly in place, as in pic 10. Trim excess conductive thread.
Step 5: Positive Trace and Battery Holder
Cut the thread, the next stitching must be separate. Thread the needle with another piece of conductive thread, 8-10 inches is plenty for this one.
Similarly to how the first magnetic snap half was placed, put in another half (making sure it's a coordinating half not a matching one) where the first half sits when the tongue is folded down. Wrap the non-needle end of the conductive thread around it when installing. See the pictures for this, it's clearer. Now sew the trace from the snap part to the underside of the battery and stitch it firmly to the negative terminal.
Your LED circuit is now complete. Put a coin cell battery in the holder and test it by snapping the snap closed.
Step 6: More Gluing
- small velcro strips to keep the battery holder closed
- around the tongue edges up to the squirrel body edge
- red felt X's over the LEDs
Step 7: Tire Track EL Wire
EL wire is a composite of a medium wire (20 gauge or so, it does vary some) with a phosphorus coating, a tiny outer wire in a very small gauge, and a clear plastic coating around the whole thing. You can make fairly sharp bends in it without a significant risk of damage. There are several useful instructables on dealing with it but here I will assume you have an EL wire, driver, and battery kit which is readily available in many places on and off the internet.
If you have a wire connector between the wire and the battery/driver, detach it as the weight of the driver makes it slightly annoying to work with. If it's soldered directly, though, you can manage OK. Starting with the driver/battery end, and at the part of the squirrel that will be down, pin and bend the EL wire into tire track shapes across the squirrel's back. You may need to make minor adjustments as you go along, or if your wire is too long or too short and ends in the middle of a treadmark!
Using regular, non-conductive thread in an inconspicuous color, sew 3 or 4 stitches over each corner of the EL wire shape. See the last pic for a closeup. I found a beading needle was good for this as it is really long. There is no need to make knots and cut the thread between each point; it is much more efficient to just carry the thread under the body material to the next stitching point.
Here's the front pic again, the patch on a completed pack cover - the EL wire battery pack and driver is inside, with the wire carefully sewn through the seam of the cover. Not that you can see that in this pic, alas.