Here is the tutorial
Make two circles.
Use region command and select all. Now use subtract command to subtract smaller circle from larger circle.
Revolve it about Y-axis at 90º.
Make two circles here of 30mm and 20mm radius and region them. Subtract the smaller circle from larger circle. Use center snapping if needed. For center snapping select circle tool and then CTRL+right click and select center. Now when you hover the mouse over a circle it will snap to the centr
Again use region command and select all. Subtract the smaller circle from larger circle. Then extrude the region by 5mm.
Use copy command and select the extruded body. Keep the base and target point same. Now use rotate3d command with Y-axis and select the extrude body and rotate it by 90º.
Now use union command to join all bodies.