DP Review posted this piece about using a lens from a disposable Kodak camera, which was popular 30 years ago, with our modern age models. It looks rather easy from this video.
This one is a bit geeky, but fascinating nevertheless. Hackaday published this piece by Danie Conradie where he makes a huge lens system for his digital camera out of aluminum sheets, 3D printed parts, and a unique projector lens. It was fun to watch. Who will be the first to make one, themselves?