: This should be what you are looking for:
: http://www.duckworksmagazine.com/articles/foldingkayak/

: PGJ

Actually, there was a plan for a folding plywood kayak but I believe it was published by Mechanix Illustrated in the mid '70's. Though I do not know where that info. is on the 'net (assuming it is) and my dad's old collection of MI, PS, PM and other mags. are gone (*he* trashed them, I'm a pack-rat, I'd have kept them).

Below should be a link to a bunch of boating plans, scroll down to the Plyak. I kind of remember the MI folding kayak being similar in looks to that one. The Plyak does not fold and I would not use the Plyak plans, though, it seems to me to be too heavy. You'd be better off with one of the S&G kayak plans, IMHO sold on this website and elsewhere. Also, the Canvasback, mentioned earlier, and the King Canvasback (an upsized Canvasback) plans are also on that site. You may want to consider those plans as well, although they are skin on frame kayaks. FWIW, my dad and I built two of the Canvasbacks, scaled up for adults (he did not have the issue with the King Canvasback, we scaled the original up ourselves), back when I was in HS. They were nice kayaks, except we made the mistake of skinning them with Fiberglass. Made them too heavy. My next SOF kayak will be much lighter. I'll skin it with something like PVC coated Polyester or something that lasts longer than canvas.

Good luck,
Paul

PS. If your husband is set on that particular kayak, you may want to try the library microfiche library. One caveat, if your local library does not keep periodicals back that far, you may have to pay a visit to the regional depository library (forgot the proper name) which should have the older periodicals on microfiche. I found this out looking for plans to build a power hacksaw for my other hobby, but now I'm getting OT.