How long does it take to make an MLO?

Weeks for a usable model. Months for a polished, finished one.

GTA MLO Creation Process: The Workflow

High-level steps involved in creating an MLO. This isn't a click-through, as the tooling changes frequently. The process itself remains constant.

Model the interior geometry in 3ds Max or Blender. Walls, floors, props and a custom lighting rig. UV map the textures.

Export the geometry to GTA file formats - YDR for the drawable model, YBN for collision.

Use CodeWalker to drop your MLO into the game world. Place the portal that links the outside door to the interior space. Tag the interior.

Load up the modded game and test entry/exit, lighting, sound etc. Iterate as needed.