Seeking all advice please?

I may be a guy, but I recently have a desire to make a new toy for Barbie as a way to start a business. My idea is a submarine for the doll that would be just under three feet long and seven inches in diameter. Two dolls would sit inside tandem seating, each with a control console. A clear plastic dome bow would allow for 360 forward vision and a small side window on each side for back seater. A fold-back lid on top would allow full easy access to interior. Have tried to make out of wood, want to get a plastic model made for experimentation.