"d" bows take advantage of more working limb, which keeps from overworking limbs in most cases. if youre following the build you posted a link to youll be fine, i also started building using sams site. after you get a few done you can start toying with dimensions and handle styles, etc.. till you find what style you like building , then just experiment with diferent stuff. really the sky is the limit once you get the basics down, and sams site will steer you in the right direction. if you are still set on a "d" bow, georges site has great information, although if you already glued on a block for the handle its probably too late to build one unless you plan on taking it off.