Just a heads up to the DIY board builders, some surfboard builders have been having really good results using Cork (Corecork - http://www.corecork.amorim.com/
) as deck skins and using it built up as rails.
You can use it similar to how you'd use Corecell.
It's good stuff, easy to work with and, especially for kiteboarding, has really good damping properties to take the chatter out of choppy conditions.
I've been riding a cork deck surfboard for about 6 months now and have been really happy with it.
The other cool thing is you can leave the top exposed for traction, since it's waterproof. Not as important with kiteboards, but will save you a good bit of money if used that way on a SUP, since you won't need deck traction.
Just thought I'd throw it out there as food for thought, seems to be a pretty progressive bunch here and I'm sure someone can find a good application for it in kiteboards.