First of all you will need a PCG Data asset, it can be created from a right click on a level instance asset in the content browser. Follow these two steps:
1) Create a level instance with a bunch of StaticMesh Actors selected, then right click ⇒ Level ⇒ Create Level Instance.
A Level instance is a regular Level which can be used in other level (more infos here).
Actors of the level instance must have an Actor tag properly set to bind them to a variant definition (random XForm, mesh, etc).
Example of actor tags.
Where to set actor tag on static mesh actors.
To easily set tags on actors, check Actor Tags manager (available on fab) !
Create of a level instance from selected Actor(s).
The tool works with Packed level instance as well as Level Instance but keep in mind than other actors than static mesh actors in a Level Instance will be ignored.
2) Then you can create PCG Data asset from level instance by a right click on the level instance asset in the content browser.
By default it saves it on the same folder with a _PCG prefix. It's perfectly fine but you can of course save it wherever you want.
3) You create a new Random Assembly Defintion and add the freshly created PCG Data Asset in its PCG Asset entry:
You can edit a level instance content directly from the edit button on the level instance actor:
Warning:
If you update the content of the level instance, (tags, or adding / removing actors), you'll need to update the PCG Data Asset accordingly either from:
