Here is an idea on making a simple Tilt Switch. (aka Inclinometer)
It would be cheap and contains no mercury
The Idea is So:-
Take a clear tube either flexible tube or curved glass tube.
Place an infrared Detector (led) at both ends.
Place an infrared Transmitter to shine in the middle part.
The inside of the tube should be filled with a semi dark liquid or thick oil ......
..... the important thing is to make sure that there is an "Air-Bubble" in the tube.