Quote Originally Posted by ME Super View Post
Slide projectors can be made quite simply. They're little more than a bright light bulb, a fan to cool the bulb, something to hold the slide, and a couple lenses. One is a condensor lens that goes between the bulb and the slide, the other is the usual lens to focus the image. Oh and I forgot about the hot mirror which passes visible light but blocks infrared.

Hmm, come to think of it, with the advances in light bulb technology and LEDs, the cooling fan and hot mirror may become unnecessary altogether, which reduces the complexity to a light source, a condensor lens, a slide stage, and a focusing lens. I've even seen instructables on how to build a simple slide projector. Projectors I'm not worried about. I'd be more concerned about cameras, film, and chemistry availability.

The Slide Curmudgeon, aka ME Super
You still need a cooling fan with an LED for equivalent lumens. It's just that it vents out the back. There are projectors out now with this. You sometimes see them in storefronts projecting cutout images onto streets etc. I've seen one at a show. Kind of cool, but low-grade optics for projecting illustrations, not fine detailed slides. The white balance would likely need an intermediary. It's the optics of slide projection that are the difficult part.