Abstract: A circle drafting instrument (A) comprises a support member (12) rotatably mounting a slotted disk (10). A line forming point (50) is positioned in a slot (B) at a selected distance from a center point (36) of disk (10). Slot B has offset apexes (44a, 46a) incremental radially along disk (10) for precision circle drafting. Additional slots (C, D, E) may also be provided for a larger number of increments. The forming point and the disk are rotated in the support so as to form a circle of a desired size.