So about ten years ago I fabbed upped a headliner using foam insulation and headliner material, glued them together with contact adhesive (when it was legal in California), it held and looked good for a few years then the material started breaking down and falling, so I tore it down. Here is my solution I went to tap plastics and got some 1/4" sheet ABS, can't remember the size (that's not important) so anyways it was 1 1/4 larger then the opening. I managed to cram it in there and eh, looks good, small amount of sag in the middle but hardly noticeable. Yeah, yeah, yeah... 85$, that's what it cost.Terry, I'll stop by one of these days.
That's the old foam one ten years ago
That's the ABS one