Yes, they are mostly cardboard but, they are all not awful.
Look for "bowtie bits" on ebay and they have a really good set for about $30 which is what I used. I ruined two others from the usual vendors and then found this one.
I think the trick is to pre-shape the headliner and install it as one piece. Mine popped in a couple of minutes and is better than I ever thought could have been achieved from with lowly cardboard.

https://www.stovebolt.com/ubbthread...in=107770&Number=1050490#Post1050490


1951 Chevy 3100 5-Window
"Howard"
In the Stovebolt Gallery
More pix on Photobucket