I like this effect because it is cheap to build, yet so effective. As the audience walks down the hallway, they step onto a board that teeters back and forth. This is really effective in complete darkness.

Constructing this one is simple. Nail or screw a long 4 x 4 down the exact center of one of your hallways. Next you are going to cut little blocks of wood that are to be used as stops to limit the amount of teetering action the effect has. Once those are cut, nail or screw them in a couple places on each side of the hallway, along the outer edge (See the illustration). You may have to experiment with the size of blocks to get the right amount of teetering action. Cut a piece of plywood the same length as the 4 x 4 and the same width as your hallway and place it on top of the 4 x 4. Put nails (not screws!) every six inches or so down the length of the 4 x 4 in the exact middle. The nails allow the flexibility of the teetering action and also make a neat creaking sound when someone steps on the board! It is important to note that you will have to build special ramps on both sides of the effect so no one trips and hurts themselves.