Uses for old slide projectors?

Slide projectors are being tossed right and left. Soon they'll be as
scarce as typewriters and buggy whips. Has anyone come up with
interesting uses for their optics or other components?

David Takemoto-Weerts
JPL Solar System Ambassador
Nat'l Assoc. of Rocketry, Level 1 Hi-power
Davis/UC Davis Astronomy Clubs
Davis, CA