Matt, I would use the densest wood you can find, the arrow will have such low mass as it is it will have problems fighting the fletches. I had some water buffalo horn sliced up into .010 thicknesses for fletches but I don't have any left. something very stiff and thin and maybe 1/8 high. paper might work. Tonkin cane is almost double the density of wood if you could find some short pieces of that.