Calipers (Proportional)- 18"18" Proportional Calipers (Stainless) These calipers are made of high grade stainless steel and are designed to give you many years of trustable service. Proportional calipers are most commonly used when working from a live model and 'scaling down' to a smaller than life sculpture but the reverse is also true. They can also be used to 'scale up'. The calipers can be used in two configurations. The standard method is for outside measurements. Typically