Boulder Boat Works does indeed sell hull kits...
Do It Yourself Drift Boat Kits - Build Your Own Custom Driftboat | Drift Boats, Boat Kits, Fly Fishing Driftboats, River Dory | Boulder Boat Works, Inc.
These are thermo welded HDPE plastic hulls that are indestrucatable. Get the durability of a plastic hull and the beauty of a wood boat all in one sweet package. I've been rowing a Boulder Boat Works drift boat for about 4 years now and wouldn't trade it for anything. Andy is an amazing designer and craftman and stands behind his product 100% (like lifetime warranty against leaks and punctures, if the hull ever leaks Andy will fix for free.)
Heres some pic's of completed boats from Andy's web site, my boat id shown in the upper 3 photos (with the rope seats.) These are examples of Andy's fine craftsmanship, not mine.
Boulder Boat Works, Inc. - Custom Drift Boat Features Page #1
I have broadsided large boulders in this boat with enough force to break some of the inner wood struts. At first there was a big dent in the hull, by morning the plastic had returned to its origonal shape and all I could find was a small scratch at the point of impact. In a wood sided boat I would have been rebuilding the hull river side...
Unfortunatly the cost of the HDPE sheeting and the cost of the thermo welding equitpment put building your own hull beyond most Do-it-yourselfer's. The manufactor required minumum orders of 100 sheets and the plastic welding equiptment runs around $2000. ( I wanted to use the material to make a dry box & custom cooler, so I looked into it..)
Andy used to make a Grand Canyon River Dory with double thick sides, full top deck and an electric sump. He stopped making them on spec because demand was low, I bet he would still make one as a custom order.
I've seen the roto-molded boats out of Steamboat, very durable but definatly second place in aesthetics compared to the Boulder Boatworks dory's.