He's right too, 3M does make some decent adhesives you just cant use their "general" trim adhesive for that, even recomends on the can not too, the way I look at it for about 45 dollars you can have the gun and more than enough to do an suv headliner, I did this to my Grand Cherokee and had roughly a paint guns load left, and if you do go to recover anything else like a box or your trim panels you still have the gun( just run some wax and grease remover through it to degunk it) which you can still use and another gallon is alot for all that other stuff. anyway point is 45 dollars to get it done that way(22 for glue), or 15 to 30 depending on what kind of headliner with cans and then more if you do run out. O and I did mean I sprayed it outside then brought it, you could put it on its side too the idea is just to let it setup with no pull on it, however for my sun roof i used the brush on version with a precut piece of fabric and that stuck real well and I was sitting in the seat doin it while it was still in(huge PIA to remove), either way is fine I just know I'm goin to be doin this to other vehicles and that glue is tried and true, professionals used it and I actually found out about it from this forum through what some of the senior members have done