you can only edit objects on existing maps not make maps to edit go on forge mode.
You cannot make your own maps in Halo: ODST, it doesn't contain forge world. Halo 3, Halo: Reach and Halo 4 all contain forge world.
If you mean making your own map, it's Forge mode.
You need to do forge to create your maps in halo 3
i am VERY sorry to inform you of this, but you cant. in halo 3, halo reach, and halo 3: complete multiplayer experience you can.
you cant
The map, Foundation, does not exist in Halo 3 and is only available in Halo 2.
Refering to halo 3 and halo reach their is a custom forge game mode, here you can build and shape your very own map creations for both custom and recreational use.
Yes, The Pit is a map that comes on disc for Halo 3.
No
No you cant
Every map in halo 3 is a good map. I perfer guardian or Blackout
muythic map pack. that comes with HALO 3: ODST