If its for an Acat then I recommend you get some epoxy and fiberglass and pink stiff foam from Home depot.
Lay some plastic or 3 or so sheets of way paper on your hulls, add epoxy and fiberglass, let harden. This gives you a nice copy of the hull for your cradle.
Glue up a 3 sheets cut to 12x12 of the pink insulation with a hot glue gun. Cut out the hull shape, it doesnt have to be perfect. Epoxy in your cradles (the ones you made off your hulls ), finish the sides with fiberglass and epoxy, sand and paint same color as your boat.
Air filled monohull fenders work good too.
My cradles are attached, work in progress, not finished. It gives you an idea of what I'm talking about.
