Years ago I used this effect in a silk routine I did as a club act, and running across it in my scrapbook reminded me that it was still good.

Two glasses are on your table together with two cylindric covers which are about a half inch less in height than the glasses. The covers are first tossed to someone and received back after you have passed one of the glasses out and had the spectator bring it back.

Taking one of the covers, you pick up the other glass and show that they just fit nicely over the tumblers. The spectator’s glass is covered and he holds it on his outstretched hand. A silk is now taken, put into the other glass and covered. On command, the silk vanishes. The tube is carefully lifted, showing the glass empty and the tumbler is set down while the tube is taken to the front and then snapped into the audience. Lifting the other tube from the hand of the spectator, the silk is found in that glass and all is well.

My method was to have one a mirror glass and the other to match but unprepared. The duplicate silk was pleated across and then up so as to spring open, tied with a single piece of weak thread and fastened to the head of a common bent pin so that when hanging inside a glass, a mere push downward on the bundle with a finger would break it. This was hung in the back part of the mirror glass. Taking back a tube, it was dropped over this empty (?) glass for a second and being a little shorter, came below the overhanging pin. Lifting it off carried the silk with it and in putting this tube over the other glass, the thread was broken by the right second finger which was holding the tube from the inside with the thumb outside. The other silk was vanished by the mirror glass !

The sucker working of being careful with the tube carried all thoughts away from this tumbler which was left on the table.