This looks a bit like a cross between Richard Butz' the "six-hour Canoe" and the "Weekend Skiff". There are books on how to build both through WoodenBoat http://www.woodenboatstore.com/store/, though I think you could probably build a shortened, hybrid, "quickie" version without the books. I'd probably rip both of the 2x4s in half and use two of the resulting 2x2's as as chine logs, cut the stem and stern pieces from one of the others, use the remaining 2x2 and plywood scraps for a paddle. Nail it together, seal the seams inside and out with duct tape and make sure you have a pfd.

Good luck and post pictures.

Marcel