his practice in architectural and autonomous stained glass, often on a monumental scale (three of his works have successively held the position of largest stained glass work in the world, and the stamford cone was the largest free-standing glass structure ever made), has led to successive innovation and invention in the fabrication of the medium, including the early use of screen printing, incorporation of photography, the pioneering of a 'dramatically enhanced pointillism', and the creation of sculptural stained glass works, analogous to collage, made primarily or entirely of lead.