I, too, did door panels about 3 years ago using the Ensolite. I still have about 25sq ft of it w/out adhesive, along w/spray adhesive. Planning on doing the door panels with those shortly. However, I ordered some a few weeks ago for a little project I'm working on, and it comes 1) in sections now, no more cut offs from the roll and 2) it is adhesive backed.
Disposable razor blades are your friend