Abe Morrell was our featured speaker last year at a PHSNE gathering in Boston. His work is amazing. The thing to remember in planning to do anything like this is that the room will be so very dim that any photographic exposure of the image on the wall (film) will take a long time. Minutes, not seconds.
As for Hockney and the use of mirrors and lenses by Renaissance artists, the tool most cited is the Camera Lucida, not Obscura- a very different animal indeed, but equally cool. The concave mirror technique works as well for projecting a high key lighted area onto a white surface in a darker part of the room. Try it with a make-up mirror.
* I'm an analogue enthusiast, trying not to fall into the digital abyss.
* My favorite cameras: Mamiya C330f, Nikon S2, Hasselblad SWC, Leica SL, Leica M7, Russian FKD 18x24, Bronica SQ-B and RF645, Rolleiflex T, Nikon F4s, Olympus Pen FT, Agfa Clack and my pinhole cameras.