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Old 03-21-2008, 04:57 PM   #4 (permalink)
Otto
Master EcoModder
 
Join Date: Mar 2008
Location: USA
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Quote:
Originally Posted by LostCause View Post
The best shape is definately going to be a tear drop. Per dollar spent, I think you would see the biggest effect.

Phil Knox's Truck


Simple, Quality:
1/2" Foam Board,
Fiberglass,
Epoxy Resin

composite construction, faceted sides

Simple, Cheap:
Lightweight Tubular Skeleton
Coroplast skin
Duct Tape

faceted sides

If you just want a normal tonneau, you could buy a bunch of aluminum siding and pop-rivet yourself one by forming ribs w/ flanges attached to skins. Cheap, easy, and unique...

- LostCause

Polyester resin is much cheaper than epoxy, and would be fine for this application as long as it's chemically compatible with the foam. Check first. Most fiberglass boats are made with this stuff, and have been sitting in the weather for decades, apparently without ill effects. Any marine hardware store or hobby shop should have it. To get the smoothest surface, do the fiberglass layup on a plexiglass sheet, then while still wet, lay the foam sheet onto that, then vacuum bag it down tight until the resin sets up. When it comes off, it'll be as smooth as the plexiglass. Then do the opposite side of the sandwich panel in the same way.

Vinylester resin is cheaper than epoxy, but more expensive than polyester resin. Where strength is a major factor, vinylester resin has about the same strength as epoxy, unless heat cured in an autoclave, where epoxy is the best.
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