proportional divider
scale divider

Mimicry using tools such as a proportional divider (sometimes called a variscaler)

Its adherents, who so far are predominantly white men, may be spotted wielding proportional dividers, compass-like instruments used for measuring ratios.

Indirect carving is a way of carving by using an accurate clay, wax or plaster model, which is then copied with the use of a compass or proportional dividers or a pointing machine.

I attacked her with proportional dividers, planimeter, rotameter, Simpson's rule, Froude's coefficients, Dixon Kemp's formulae, series, curves, differentials, and all the appliances of modern yacht designing, and she emerged from the ordeal a theoretically perfect boat.