The method is clever, really simple but clever. However, the gimmick can be seen at times. You will
need to set it up right before you can perform it. This could be set up on the spot, but it is not
examinable and it is a bit difficult to set up on the spot and have the gimmick stay hidden.
Practicality wise, this can theoretically be done close-up, but it is easy to see the gimmick, so I
recommend only parlor, so it's practical if you do parlor and somehow fit it into your show, if not,
then it's not that practical.