1. Display two sticks, and insert one inside the cross shaped tube. Allow your spectator to peek inside to confirm that the stick completely fills the tube, leaving no extraneous gaps or openings.
2. Insert the other stick into the tube, and... with no resistance at all, it passes directly through the first stick! The two sticks occupy the exact same space.
3. Remove the sticks and allow your spectator to touch them at the spots where they penetrated. There is nothing to see, feel, or find!
You can also penetrate pencils, etc. through each other!