I also made the same one sdspeed posted. The only difference was I added posts to fit into the scupper holes so it won't shift or spread. I made sure everything fit and worked prior to gluing.
The posts have to be small as the scupper holes are in a slight angle. So I made them just long enough to go into the hole and the hull just lays on the pads.
I posted both carts made by Palmetto in the innovations section. This is the other one.
http://palmettokayakfishing.blogspot...ayak-cart.html