Thanks Tim.

The material is an .090 black ABS, haircell pattern one side, smooth on the other. My job required 3 ea, 4' X 8' sheets. The local shop could cut it down, but they would charge me for the cuts and wouldn't sell a partial. So I just took the whole sheets. Figured I can make side and door panels, maybe even back door panels with what is left over.

There are plenty of online sources:

http://www.sdplastics.com/abs_extruded_sheet.html
http://www.usplastic.com/catalog/item.aspx?itemid=23013

But I found it was much cheaper to source locally. Almost 1/3 the price. And, double the cost to add the shipping for the online sources.

The headliner has been in place for a coupe of weeks now. With the change in temperature, I have noticed no changes/sags or any trouble. I also put over three hundred miles on the Suburban and everything stayed in place. I'm still happy with the job and have received a lot of compliments.