Think of lead calme as tiny I-beams into whose grooves the edges of the glass fits. Lead is a soft metal that can be easily bent to shape. At intersections with other lead, the ends must be trimmed for a clean, gapless fit. This photo follows the process. First the "heart" is cut and bent back out of the way. Next both faces are trimmed to the desired angle. Finally, the heart is straightening back out the excess is trimmed.