A nut and bolt, with a tiny piece of brass pipe, and a metal tube are shown to the spectators. The magician then threads the nut on the bolt, trapping the brass pipe. The whole unit is placed into the tube and the cap is placed on top. The magician now makes a few “magical” gestures and the cap is taken off the tube, and the contents are poured out onto the table. To everyone’s amazement, the nut is no longer threaded on the bolt, and the brass tubing is now free.

Everything is then examinable.

This is a magnificent close-up effect.

This method does not use invisible thread.