Hi pete, i wrote a while back about making a foam mold within the kayak (2 part foam in garbage bag) then making the seat by sitting on the curing resin/glass. The reason for doing it that way instead of just a butt impression was to make the seat hang down from the coaming and conform to hips as well. There's a heavy bias cut fabric , not weave, that worked well for this purpose. But you just might check around for the price and availability of stock seats. It took me about 10hrs to make one. I think the seat in a Dagger Meridian is available for about $120, some of the production plastic seats might be cheaper.