This is a pretty cool trick if you can find the right surface, it has to be a smooth polished tile floor or something similar. At the magic shop I sat the box on the glass counter, engaged the gimmick, and then tried to lift it. It damn near dislodged the entire sheet of glass.
And therein lies the secret. The box doesn't have a bottom. Affixed inside the box is one of those suction-cup tools that's used to handle large sheets of glass. When the mechanism is engaged the large powerful suction cup grabs the floor. It's all but impossible to lift.
Below you'll find a link to the trick over at Murphy's. Notice there are no handles on the box. If there were they would be ripped off the box by your spectator assistant.
http://www.murphysmagic.com/Product.aspx?id=49635
I've done a Google search for these glass handler's suction cup tools. The prices are all over the board, the cheapest I found sells for around $15.oo.
Everytime I see one of these tools I think of the comedian John Candy. I forget the name of the movie, but he's got them on both hands and feet and he's clinging to the outside of a sky scraper window. lol
I just saved you $230, now you can spend your hard earned cash on other things like the latest piece of magicrap.
-Leary-