I have been looking at similar materials for a tiny trailer. Sign makers use materials that need to be able to hold up in the weather. Some of these products are aluminum clad on one or both sides. I have been looking at two in particular: Alumacorr and Poly-Metal as manufactured by Nudo.
http://www.nudo.com
The Alumacorr is the most intriguing. It is available 10mm (3/8") thick with a "corregated" polypropylene core bonded with .015 prepainted aluminum skins. If I recall correctly a 4x8 sheet weighs about 22 pounds and it is very stiff. Not a true honeycomb but similar in effect. Available in basic colors up to 4x10 feet, and in white up to 4x12 or 5x10. A 4x8 sheet (white) is approximately $105 plus shipping.
As has been discussed on other threads, the trick is how to fasten to it for a structural use and how to seal the open structure if required. Tape bonding might work. I have run some tests and the foam tape that I used was impressive. If the surface is lightly sanded to break paint gloss, Gorilla Glue and other poly products seem to bond well. Might be just the product for someone building a nanolight tear.
The Poly-Metal can be had in two thicknesses, 6mm and 3mm. The core is solid polyethylene to which .015 prepainted aluminum skins are bonded. I played with the 3mm version and it is cool. Glue your framework right to it. Not as stiff a panel as the Alumacorr, but very respectable. Also about 22 pounds for the 4x8 sheets in 3mm. Very dent resistant. The 3mm is available in colors in 4x8 size. Up to 4x10 and 4x12 in white. The 4x8 white is about $75. The 6mm probably has too much weight penalty.
Although I haven't tried it yet, the Poly-Metal should be able to be bolted or riveted as it is a solid product. This should make it much easier to fasten to. It also bonds well with tape or poly glues.
Both products can be cut with normal wood working tools (with the correct blade) as the aluminum is quite thin, yet bonded to a plastic core. The Poly-Metal conducts heat as you would imagine, with the core offering some reistance. The Alumacorr does a fairly nice job as an insulator, not like foam, but it does have some inherrent insulating qualities.
You can check out these products and others at:
http://www.alumapanel.com
They also have affordable bonding tape. I doubt that it is as good as 3M, but it might be close.
Other signage suppliers can provide these and similar products. Has anyone tried to build with these materials?