I have not made many bamboo bows, but have found that if the stuff is large diameter that you can use the outer fibers of the bamboo as the belly and the inner as the back and it helped to balance the forces as bamboo is very tension strong and the outer fibers are stronger than the inners. You tiller on the back. As for flooring, you need to look for vertical grain running the length of the board, like boards, the grain needs to be straight up and down.