Forming them is actually really easy. I knocked out the forms above for the wingtip lights in less than 30 minutes. The male form is just balsa sanded to shape CA'ed to a wooden dowel. I hardened the form with CA after rough forming it and then sanded it down with 220 grit followed by 600 grit. I cleaned the sanding dust off with alcohol and made the female form with 1/8" lite ply.

The 0.06 PET sheet is $9 for enough to make at least 20 lights and is thick enough that when "pushed" through the female mold it stays thick enough to be durable and hold its shape...

Bob