Internet image search? To me, they generally all look alike: The aluminum throttlebody bone's connected to the plenum bone's connected to four runners bones's connected to the head bone... Historically, so far as I know, there were no commercially available aftermarket intake manifolds. The H22A VTEC had some options, but not the H23Ax non-VTEC. Anything custom fabbed would probably involve either billet or sheet aluminum and welding that would stand apart from the factory cast manifold.