Anyone can map makes. There are two editors available. One at Zoo Admin and one at the Designer Guild. They allow you to move and place the gates and the zoowalls. Those maps are saved in your Saved Games folder
However if you want it to appear in Freeform Game part that is not encouraged as it requires dll ids and we ran out of them once and managed to find more but a limited amount. Those are allocated on request. Nor is there a tutorial for making a Freeform Map.
Developer Map Editor Hack from the Designer Guild
Map editor from ZA