... I like to use trains for everything.
I would make an invisible train underneith your box, not very big, so when you pressed the button, the invisible train zooms away, and the box falls. This way, you could have a reset on the train, and you could push the button multiple times. If you are doing a puzzle map, like if you have to push that box to a certain place then press the button to see if you got it, this would work best.