Making new partition for back seat/trunk area

I'm curious what some of you guys have used in place of the factory particle board crap that crumbles to dust when you touch it. I basically destroyed the original trunk divider the first time I pulled the back seats out to clean my '70 Duster. I'm thinking of some sort of "sheet" plastic maybe 1/8" thick ABS-type stuff then putting a layer of aluminum roofing repair (Poor Man's Dynamat) to reduce noise. I want something that is easy to cut so I can get it fitting in just right. Thoughts?