In my neighborhood, we have an excellent urban bike trail that runs along the a fairly large river that divides my city in half. Often, while cycling, I'll see folks, mostly elderly men, pop out onto the trail with their large canoes and kayaks.
"How fun," I always think, but there's no liveries or rentable canoe places until you drive an hour or so out of the city. Of course, I wouldn't need to rent one if I could get my hands on a piece of softwood plywood and a saw.
Which I can.
It's modeled after a South American dugout pipante, and, thankfully, Hannu has done all the math and measuring and good boat physics, and offers free building plans and a step-by-step how-to.
Find the full tutorial at: The Dug: 18 Foot One Sheet Canoe