IT WORKS! That's enough said. But you can work this twice. Yeah, yeah, you are not supposed to show
the same trick twice. So's people get the box they shake it and say it's empty. "No no! When cards
are invisible they weigh less." Do your invisible deck routine and produce their card. After that I
ask them to put the invisible deck back in the box. While people watch this I close and shift my
gaffed deck into a neutral position. Usually at this point someone says "Do that again!" I have the
first "assistant" hand the empty box to that person. Have them hold it next to their head and think
of a card, turn it backwards and tell the audience what they thought. If they think you should know
it already say "Hey we aren't mind readers" Produce the card from your deck. Then as applause dies
down ask this assistant to open the box
"the cards should be visible now". The eyes go to
him/her and no one notices you switching the gaffed deck for a regular deck. When they say "I don't
see anything". You "Dang it, It's those (new/cheap) batteries I've been using". 3 to five minutes of
jokes and magic off a $4 empty card box gimmick!