Here's a reference for price and availability of types of products. These guys are in my local Atlanta area and supply local sign shops. I'm an occasional customer, that's all...disclaimer. There should be similar suppliers in major cities to handle the local supply needs. Your local sign maker could probably arrange to get some product for you.
http://www.alumapanel.com/subcategories.cfm?step=1&lines_ID=289
Regarding the Endurex 300. If one goes to the web page woytovich posted and clicks the "
stabilizer" button near the "1, 2, 3" diagram you will note a variety of possible core materials. Whether or not Endurex is a little different from other Nudo products may be minor. Companies like Nudo will laminate all kinds of stuff for you if you want a big batch. For our purposes we need to find the "over the counter" product. Economics will favor such a product too. Other manufacturers make competitive products, this is just the brand my local guy carries.
Back to Endurex cores....
"Hardboard" core: Nudo makes a composite with aluminum skins and a plywood core called Nu-Alum. It's a nice product but fairly heavy. I've hefted a 1/2"4x8 sheet and it's got some weight to it...like 3/4" plywood.
"Composite" core: Nudo also makes 3mm and 6mm "Polymetal" which is aluminum bonded to a solid polyethylene sheet. 3mm is actually heavier than the 10mm Aluma-Corr and is much less stiff, although an interesting product. I've got a dozen sheets sitting in the garage that I will be putting to use.
"Corrugated" core: Nudo makes "Aluma-Corr" in 5mm and 10mm thickness, corrugated polypropylene core. The 5mm is not nearly as stiff as the 10mm. A 4x8 sheet of 10mm weighs something like 22#, about the same as 1/4"plywood, but quite stiff. If you take a quick glance at Nudo's page
http://www.nudo.com/Sign-Panels/Designed-Performance/AlumaCorr.aspx you'll see a vestige of a reference to Endurex 300. Probably the same stuff. Also note on AlumaPanel's site that the sheets are available larger than 4'x8"......4'x10', 4'x12', 5'x10'.
"Cement Board" & "Gypsum" cores......LOL.
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If I were to build a light TD for myself I'd be looking very strongly at Aluma-Corr. My local sign shop supplier has nearly all the materials for the body shell:
Floor: 1/2" prefinished MDO. (let them do all the coating work)
Sidewalls: 10mm Aluma-Corr white. Have the local sign shop cut two identical pieces on a CNC router, cut the doors at the same time. The corrugations would run horizontally. A few 1"x1" vertical aluminum tube stiffeners would be bonded to the interior of the walls with foam sign tape, poor man's VHB.
http://www.alumapanel.com/view_product.cfm?step=1&lines_ID=307&name=Alu-%20Tape%20Double%20Sided%20Foam%20Tape
Roof "rafters" 1" aluminum tubing. Roof material would be a single piece .040 white aluminum sheet.
Shelves and cabinets can be made of Aluma-Corr, use 1" tube (or aluminum angle) and foam tape to join perpendicular panels. A trim cap is available to close off the exposed edge of the corrugations.
Glue 1" pink insulation board between wall studs and between roof rafters and cover inside surfaces with nice cloth, perhaps.
This method would solve a lot of the problems associated with trying to stick aluminum onto plywood after a wood structure is built. It is prefinished and durable. Very light. All the aluminum will expand and contract at about the same rate and solve some problems of dissimilar metals in the upper shell. Also, there's no formaldehyde to deal with, a personal issue for me.
Some food for thought.