I got a little carried away by this image in my head:
What if, instead of putting up a giant poster that I liked, I could instead just project an image of {whatever I want to have on my wall today} directly on the wall? Especially if it can be a really big projection! (My office is about 3 meters square, with ~ 9 ft. ceilings, and I'll have one or two walls that are essentially empty.)
I know I've seen an old-style overhead projector that could project an image like a document camera, but I didn't realize how expensive the equipment would be... I also forgot how quickly bulbs wear out, so my initial idea of positioning the working parts of a document camera / projector on top of my shelf turns out to be not very practical.
So: any ideas on how to project the image from a piece of paper (like my Breaking Bounds calendar) onto my wall for less than, oh, $1,000 or so, and at a quality that's worth having on the wall?