How can I block collisions with hollow static mesh (inward normals)?

I solved the problem after watching this tutorial video: Unreal Engine 4 Tutorial: Collision (english) - YouTube

Basically, I hadn’t set up any collisions. Here’s what I did:

  1. Created a new test object in Blender: a boolean difference of an outer torus (scaled along normals) minus an inner torus, creating a hollow torus-tube with non-zero wall thickness.
  2. Exported to FBX
  3. Ran it through the FBX 2013 converter
  4. Dragged the resulting file into the Content Browser
  5. Double-clicked the imported object in the content browser
  6. In the object editor, in the details pane, under Static Mesh settings, set “Collision Complexity” to “Use Complex Collisions as Simple”
  7. From the Collision menu, chose Auto Convex Collision
  8. In the Convex Decomposition Panel, set Max Hulls to 24 and Max Hull Verts to 32
  9. Apply
  10. Tested object in the simulator, and can collide with the outside shell (starting outside), and the inside wall (starting inside).