I'm pretty set on the cardboard/fiberglass combo. It should have a great mix of lightness and strength. I called the local Costco, and they said they always have a large supply of the cardboard 'slip cards' that go between packages on pallets, and that I can pick as many up as I want if I swing by. I'm going to use those for a mock up. I'm likely going to order pristine new cardboard when I do the actual build.
I am very interested in the honeycomb cardboard. It's called Hexicomb, and I've found one place where I can get 4x8 sheets for $18.
http://www.ashleydistributors.com/corrugated.phpNot exactly free, but it should be insanely strong for the weight. The only problem I've found is that the only place I've found to buy it is in California, and they can't ship it due to size...

They did say that they have a LOT of calls from my area from people trying to get it, so I'm considering the feasibility of having a larger quantity truck shipped up here to the Seattle area, then reselling to make my money back. I'm not sure how I'd actually find the people who have been looking for the material though...
Now for the actual build planning. So far I have two challenging areas that don't apply to normal trailer builds, the windshield header and the door surrounds. The windshield header is the area where the top connects to the windshield, and the door surrounds are just as they sound, the plastic pieces that go around the doors. They are both specific contoured shapes. I want the whole thing to fit like a factory part, so I need to either reproduce the shape by making a fiberglass mold of the original, or find and purchase some used ones to incorporate into my camper. I need to keep the ones currently with my Jeep for use with the soft top if I decide to switch back for a while. I have found them for cheap before, but not consistently. Another possible option is to find a hard top that has been in a roll over or has some other damage, and buy it for those pieces. If I find one somewhere else in the country I could probably just have the seller sawzall the pieces off that I need to save on shipping. Hmm, I may have just talked my self though figuring out the easiest method. I think I'll go post on the Jeep forum
