How to make unit walk on model?

[DD_legionTN]

To be specific, how can I create a model (let's say a stair) that unit can walk on it?

I'm currently using 3dsmax 2014 version

 

[Alok]

That doesn't have to do anything with the model itself. For a doodad to be walkable set its Pathing Map to None and Is Walkable to True in the Object Editor.

Edit: However, if you want to block some areas to be climbed (like the side walls of the stairs) or to block for units to unrealistically walk over vertical walls, you have to make a fitting Pathing Map for your doodad. Here is how to do it: Custom Pathing Maps.

 

[DD_legionTN]

Ah I see, been wondering what "Is Walkable" does in object editor at start, and forgot it very soon and never touched it. About making a pathing map for a model I already know, thanks for your help

 

[Athur12A2]

There is a tutorial for that stair here.