Interesting idea for a Do It Yourself 4K Projector, and many projectors work with fresnel lenses already, but usualy such projector are cheap. http://www.instructables.com/id/World-First-DIY-Real-4k-UHD-Beam-Projector/ If there was fresnel lenses with higher resolution (smaller grooves) and made with quality optical material instead of plastic, this could be a good alternative for affordablke 4K projectors, allowing a more homogeneous image along center to the edges. Like the author of the DIY article said, he tried to use fresnel with smaller grooves, but all he tested had the same problem, probably from the matrix itself used to crete the lenses. Moderator, I'm not sure if I can post such topic here. Please forgive any mistake of mine and orient me if needed.