Create a FiveM MLO without 3ds Max: ymap, ytyp and ybn explained

For many RP servers a custom interior is the moment the city starts to feel like their own: a station, a workshop, a club. Anyone creating an MLO for the first time quickly runs into a long tool list and file extensions nobody explains. This article sorts out both and shows a route that works without 3ds Max and without modelling yourself.

What an MLO is made of

MLO stands for Multi-Level-Object, the GTA term for an interior you can walk into. A finished MLO resource consists of a few files, each with a clear job:

The classic route

The classic route is modelling the shell in Blender with the Sollumz add-on or in 3ds Max, exporting it to the GTA formats, creating rooms and portals in CodeWalker and pulling textures and templates out of the game with OpenIV. It is powerful and the right path for fully custom architecture. But it assumes you can model and know the quirks of the formats.

The Forge route: step by step

With the 5MC Forge FiveM MLO tool you draw a floor plan and Forge generates the shell, rooms, portals and collision from it. You furnish with props that already ship with the game.

1. Create a project: empty or from a GTA template such as a mansion or the Mission Row police station.
2. Paint the floor on a grid. Rooms follow from the walls you place along the grid lines.
3. Place doors, windows and passages. Openings without a door leaf automatically get a door when building, a double door from 1.5 m width.
4. Add levels, stairs, ramps and elevators if the interior has more than one floor.
5. Furnish: place props from the catalogue of around 32,000 models on floors, tables, against walls and under the ceiling, plus lights.
6. Run the check. Errors block the build; warnings point out doors in walls or furniture facing the wall.
7. Build or choose “To test server”. Forge writes ytyp, ymap, ybn, models, textures and fxmanifest.lua, plus stream_enhanced for FiveM Enhanced.

Rooms, portals and limbo

The game draws an interior room by room. Portals are the openings between them: through them you see from one room into the next. Room 0 is called limbo and stands for the outside world; every portal to the outside points to it. The ymap announces how many such exits there are, and that number must match the portals in the ytyp. If it does not, the game can crash while loading.

This bookkeeping is error-prone by hand. Forge derives rooms and portals from walls and openings, orders the portal corners the right way round and counts the exits itself.

The fxmanifest.lua of a map

For the server to load the files as a map, the resource needs two entries: this_is_a_map and the registration of the ytyp. It typically looks like this:

fx_version 'cerulean'
game 'gta5'

this_is_a_map 'yes'

data_file 'DLC_ITYP_REQUEST' 'stream/werkstatt_5mc.ytyp'

Forge writes the file itself when building. With “To test server” it puts the resource into your local FXServer and adds ensure to server.cfg; the server must be off for that.

Common errors and their cause

• The interior is invisible: usually the ymap is missing from the stream folder or the ytyp is not registered.
• You fall through the floor: the collision is missing or incomplete. For very large interiors Forge reports the number of collision points and stops with a clear message before a broken collision is produced.
• Crash on entering: often portals and announced exits do not match.
• Everything is overexposed: too much light per area. The Forge check warns about it.

Even faster: with AI

If you build many interiors, you can hand the legwork to Claude. On every Forge plan your own Claude operates the editor via MCP. How that works is on Build an MLO with AI and in the tutorial Build an MLO with Claude.

Justin Beil

Founder of 5MCustoms

Justin has been building FiveM servers, vehicles and interiors for years. 5MC Forge is the tool that grew out of it. What you read here comes from practice, not from a product sheet.

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