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You should have got the fan shroud from the car with the fan, and fitted it to the opening' making it much more effective.
Why not use a black plastic bucket ? The black disc in the bottom is only effective if the suns rays manage to hit it directly.A tall beaker would also allow collecting more desalinated water.All this talk about Zinc is way off the topic.
You could also use 10 Ga. 6/6 WWM concrete reinforcing, which comes in 5' x 50' rolls. No transportation problems either. You can get 8 -18" sq. or 10 -19" dia. cages from 1 roll. Round is easier just cut 60" from the roll and tie the ends together.
You do not need drawings for this bench, it is a simple straight forward project. You can determine your own dimensions to suit your application. The original used half lap joinery but dowelling or mortise and tenon gives a more finished appearance. There is a design flaw in my opinion, the legs should flair out from the seat to the foot not in. The original design is unstable and subject to tipping, under certain conditions. The cost of materials can vary considerably depending on the material chozen, the origianal I believe was Beech wood.
You can clean the labels off quickly and easily with Acetone or Goof Off . Not green though !
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