Well the only possible way you could make a real Mezzaluna, is if you were the luthier who already buids them, and since you are asking for help with it, that doesn't seem likely. The most you could hope for is a Mezzaluna clone (but what is the fun of repicating what already exists, really?), or a Mezzaluna influenced bass.
It apears there is a very good amount of info on that in that article. and blueprints in the clickables. it seems to have some ergonomic qualities, but there is more that could be done to make it more erganomic, if that is your goal. Look up erganomic instruments in general.