The hinges must be the kind for attaching inside of the box. If ordinary butts are used, the cover of the box must be cut as much short as the thickness of the end board. The hinges should have pins that will slip easily through the parts.
Illustration: Box with Hinges and Lock
Before entering the box the performer conceals the buttonhook on his person, and as soon as the cover is closed and locked, and the box placed in a cabinet or behind a screen, he pushes the pin or bolt of the hinge out far enough to engage the knob end with the buttonhook which is used to pull the pin from the hinge. Both hinges are treated in this manner and the cover pushed up, allowing the performer to get out and unlock the padlocks with a duplicate key. The bolts are replaced in the hinges, the box locked and the performer steps out in view.