Making holes in 3D objects (Unity)

How can I make a hole in an object with Unity 3D? I've something like this object and I want to make a hole in it.

Answer

You can't. Unity does not have CSG modeling options. You're going to either:

1. construct your cylinder out of smaller parts


2. model it in another program


3. programmatically rebuild the mesh geometry at runtime. WARNING: ADVANCED TOPIC