Andy George made his own camera lens with borax, river sand, and soda ash. From PetaPixel:
"It has been one of the most challenging projects I've ever done," George says after completing his lens. "Every single step in the project has been a huge pain."
Making clear glass took over a dozen tries, annealing the glass pucks took at least four attempts, and grinding the lenses themselves took at least 30 hours of continuous grinding.
Sure, the lens is cloudy and, er, imperfect, but HE MADE HIS OWN DAMN CAMERA LENS FROM SCRATCH!