Materials suggestion......

[Benny]

I need a material that can be molded, will withstand 25 years weathering, is cheap, wont rust or corrode.
Any suggestions other than asbestos ?

[Graham Waterworth]

Clay

Graham.

[fisherjim]

If you mean a plastic material try UHMWPE, or if a metal how about Navel brass?

Jim.

[Benny]

Maybe I should have been more specific, I want to make a frame for this sort of solar collector.
I am thinking in terms of third world countries. Where the amount of steel is reduced to the bare minimum.
I was even wondering about glues that could bind soil together

[Benny]

Graham, clay is very third world. and a good suggestion.
Jim I have just read about UHMWPE  http://en.wikipedia.org/wiki/Ultra_high_molecular_weight_polyethylene. It sound like an amazing material. Is it costly?

I would like to make the frame as one big mold. This would save on labor costs as well as steel costs. Since molding is just a matter of pouring material into it, it would be a fast and efficient method.
All the swivel components might be able to be made out of that UHMWPE.

Maybe concrete might even be viable? Any further suggestions would be appreciated.

[BluePinnacle]

Wood? Pretty robust and cheap. Wood plus concrete would be nice and stable.

[Overloaded]

FRP...Fiberglass Reinforced Plastic.
Make the mold....Spray in a release agent then a Gel Coat with UV inhibitors.....Then spray it up with Glass Roving through a Chopper Gun.
Use Polyester resin, it's cheap. Will last a   l o n g   time.

[BluePinnacle]

good point, FRP is very strong.

There's the added advantage that metal parts like pins, hinges, cable clips etc. can be moulded directly in without screwing or bolting.

[Sam]

prolly needs to repel moisture, remain stable at extreme heat, and a multitude of other elements for 25 years, too, hugh. Might try digging around NASA and other aerospace sites for some advise. Maybe make a few phone calls. Never hurts to try. Completely off topic...It's hard to imagine 25 years from now that solar collection is not vastly different than today, or even 15 years from now.