How to make a Heating and Cooling Jacket

Step 13 Preparing your Shell Holes

You now need to make holes in the shell, sew felt to the outside, and attach Velcro to the inside for the fans.

1.       Cut four holes, each the same diameter as before, in the liner where you would like to put your fans. We placed two on the chest and two on the lower back.

2.       Zip the liner and shell together and cut the four holes in the liner. Zipping them together before cutting will insure that the holes line up well.

3.       Out of the flexible felt squares, cut four felt rings—make each one two centimeters thick with the inner diameter the same as or a little less than the fans. Sew these rings to the outside of each of the shell holes in order to keep the two shell layers together.

4.       On the inside of the shell, sew the fuzzy Velcro around the circumference of the holes. I found it easier to cut slits about every two centimeters so that the Velcro lays flat in a circle. Make sure to sew it on very well—otherwise it could rip off later on.