I did a coat a couple years ago ...
(the back has a pyramid with a question mark inside in two colors) and, to get tight, straight lines, I backed it with plastic crochet mesh. It's just a plastic grid with about 1/8 inch (3mm) spacing. I'd suggest getting a pre-made kit and just keep everything as-is (e.g. don't even cut the EL wire shorter.)
Oh yeah, and I used fishing line to stitch it.
Things I learned:
- It's easier to use heat-shrink tubing over parts you want to be dark than it is to cut it and solder on new connections (e.g. the gap between the two parts of the question mark.)
- Don't cut the outside to make tight corners. Rather, make a loop inside the fabric with heat-shrink over it.
- It eventually fails. If you treat it well, it will last a few years.
- If you turn on the inverter without wire connected, it will commit suicide.
You do not have the required permissions to view the files attached to this post.