Ideas for hole in the floor

[sneeky]

In the industrial/steam punk section of my haunt I have an 8" hole in the floor with about a two foot space beneath it. I want to use it for a scare. What would you do? Have something pop up, air, steam or something more creative?

[Front Yard Fright]

First thought would be a endless tunnel illusion using two way mirrors. Otherwise, depending on budget, perhaps a motion platform that moves?

[drfrightner]

You know I would consider putting a grate over the floor so people can walk over it... but I can think of a zillion things you could do from an air cannon in the floor that blasts up at them, a giant squire fan that blasts them with air to something with high sound, to just about a hundred other things. Larry