I also made Frostline kits when I was a kid. From 7th or 8th grade all through high school and into college.

Lets see, I made a few day packs, a full backpack, a foam pad (cover), insulated booties, a non-insulated jacket, a thin down insulated coat, a super thick down insulated parka, a down sleeping bag, and a 2-person tent. I still have most of it, though they haven't been used lately.

Sewing is a great skill, but designing good gear on one's own would be pretty tough. I sure wish Frostline was still in existence.