I used these
https://www.amazon.com/Noico-Insulat...a-806533907915 under my carpet and they are super sticky squares of foam stuff. I got to wondering as I was applying them, if there would be some way to utilize them in constructing a headliner. If somehow they could be laid out to form and then covered pehaps with a lightweight piece of fiberboad or palstic that you would glue to the non-sticky side then maybe wrap it with vinyl or cloth using the peel and stick side on the back to hold the material where it wraps over. Then peel the paper away from the back of the product and stick it up there.