Borrow a small object from your spectator. Tie it with a rubberband on a playing card.

In this condition it's impossible for that object to move anywhere, but in just the blink of an eye it can visually vanish.

Hostage is a innocent looking gimmick that allows you to vanish an various object openly. It's fun to build and practical to use. You can easily perform it as a stand-alone effect or on your repertoire.