Instead of sand use plaster of paris. Put it in a low box, sit in it, let harden and then (band) saw it into strips and take the profile from them.
JohnK

: I am starting to think about what kind of seat I should put in the
: kayak I am building (Nomad by Björn Thomasson).
: On Nick's website I have found a picture gallery with a wooden
: seat:
:
: http://www.guillemot-kayaks.com/guillemot/index.php?q=gallery&g2_itemId=1362.
: I looks great. Maybe i'll build something like that.
: The pictures explains most of the building process, but I can't
: figure out how to determine the shape of the section patterns
: (First picture in the gallery). I think I know how to make a
: mold of my bottom (something about sitting in a pile of sand),
: but how do I transfer that mold to the paper?

: Palle Dam
: Denmark