In leathercraft, a "thumb" usually refers to a (also called a pear shader).
Based on your description, you're likely looking at items related to , where these specific terms refer to tools, techniques, and materials: Leather Tooling and "Thumb" Tools leather trannies thumbs
: For reusable patterns, many use "solid" or heavy-duty materials like posterboard or Bontex , which mimic the way leather bends during test fittings. In leathercraft, a "thumb" usually refers to a