For instance :
Starting from a circle :
- Add a circle
- In edit mode (Tab) extrude E and stay in place (Esc or RMB)
- Scale S
- Select all and extrude again E
Or from a cylinder :
- Add it
- Remove top and bottom the faces
- Then same principles as above
Or using curves :
- Add a plane
- Keep only the edges X the 'only faces'
- Back to object mode convert it to a curve Alt+C then curve from mesh
- Add a bezier circle curve
- Set the previous plane as bevel object
- Tuning : move the plane vertices (or scale or other) to make the hole appear (here in edit mode, select all then grab along X)
Another one !! Using spin tool :
- Add a plane
- Keep only the edges
- In edit mode offset it (and eventually scale it)
- Go in front view (viewing the plane on its side)
- Then spin tool Alt+R, set the rotation, the amount of steps
- Remove double (for the last step which overlaps)
