Magnets instead of clips I used magnets like Andy mentions to attach a headliner in a mid-sixties Dodge pickup. If anyone knows these trucks, you also know how there’s an inner “wall” around the majority of the upper cab area, but an opening overhead. The magnets were the best option vs fabbing a structure to hold the headliner piece in the opening. I laid out a grid of magnets, attached with machine screws and nuts w/ a little loctite, to my luan backer and covered the panel. When I installed it, the magnets were strong enough to pull the panel in place when I got about an inch away from the surface. I’m confident the panel is secure and the grid of magnets will eliminate any potential sag as the interior gets some age on it.