Hmmmm reading your description, it may be not possible if you want to create custom volumes based on the mesh but you can create custom volumes/collision boxes in the static mesh editor then Collision->Choose whatever option you want. There’s a convex collision generator there.
First, thank you for your answer. That help me a lot.
But I have a new question. I saw that Geometry Editing could change the shape of volume, and the Pen can place a vertex, but I don’t know how to place a vertex on a volume box. I tried to press space bar to palce a vertex, however, it is useless. Could you tell me how to place a vertex on the volume boxes?
Thank you again.