Thanks, all.

Now I have a confession to make. It was really, really off-topic. Like I posted elsewhere http://www.cpakayaker.com/forums/viewtopic.php?f=15&t=5275 I want to start by making ice skates that actually fit me.

A boat is a lot more ambitious. If I made one, what I'd really like would be a lightweight folder I could keep in my car.

I bought Jeffrey Ward's rolling SOF that he made for himself. $400 was a very fair price, and it's light enough for me to carry, and very well made, though I wouldn't dare do a T rescue. But he made it for himself and he is a lot bigger than me (more than a foot taller, a few inches wider and somewhat heavier), so it doesn't handle quite right - hard to steer, not at all playful, and farther out of the water than it "should" be. I like keyhole cockpits better than its ocean C.P. too. At 19' long and black it is also dangerous to park - too easy for someone to accidentally run into and destroy, so I hate to leave it on my car.

The commercial folding kayaks aren't fast enough for me to use to keep up with the clubs I sometimes paddle with, and are surprisingly expensive.

I don't see anyway to make a folder with composite construction. I guess poles (wonder if I could use aluminum or carbon tent poles...) and coated fabric are probably easiest, but that is a lot more ambitious project than I am ready for. I don't even know how to sew, let alone create fitted ends onto poles.