Do you mind opening it up and taking and posting some pics of the pcb to see which type it is and if there are any changes made to it?You mean like this one?
I don't know exactly how it's made, I only know it can be bought
I also know for a fact that the guy doing this, can also copy you two naomi games (gd or cart) or 4 atomiswave of your choice to a single Naomi cart.