Bronco Info: 94 C150 prerunner 351/zf/maf. To many mods to list.
I went to joannes fabrics and got 1/2 thick high density foam. Its carvable and shapes nicely. Dont leave harsh edeges keep them rounded or the fabric wont stick right. And keep the details to a minimum to many intricate shapes in a small space will leave you with unsatifactory results. So try to keep them large in size and simple. Last one i did was an eagle talon and it was simple script that said talon. IIRC i used 3m super 77 spray adhesive or lock tite. Try to find a spray that is clear in color so it wont bleed through into the fabric. Spray the headliner and spray the fabric. Then walk away for a minute or two come back and start spreading. Flat liners are easy as pie, shaped ones take more time.
I recently re-did my headliner using a real tree style camo fabric that I got from Wally World and 3M adhesive. Came out nice too. There is a pretty detailed thread floating around somewhere of a guy who covers the whole thing step by step..need to snap some pics of mine..