Boat parts

Looking for someone to help me design an outboard motor offshore bracket. I think it should be pretty straightforward. The part will attach to the transom of the boat which has a 10° angle. It will extend 12 inches from the transom of the boat. The purpose of this part is to add extra flotation and also give a place to mount the outboard motor at the proper height. For examples please look up Armstrong bracket. More measurements and pictures available upon request. I would like these part designed so that the individual pieces can be CNC cut out of aluminum and then welded together. Each surface should have a way to interlock with the other surfaces as a jig will not be used.