Traditionally, rugby balls were created by stitching four panels of leather by hand around a pig bladder, although sometimes six or eight panels were used instead. The bladder was then inflated with air and sealed. This led to a wide variety in the shape and size of rugby balls when the game was being finalized. Most had a roughly oval or round shape given by the pig's bladder, but there was no set standard for shape and the oval cast of modern rugby balls was beyond the skill of original leather workers.