Drafting tool

A drafting tool made of a rectangular piece of flat transparent material having a predetermined length and a predetermined width for use with a marking instrument including in combination:

• first and second straight parallel reference edges comprising the outer edges of the length of said tool;
• a protractor base line marked on said tool and spaced from and parallel to said first and second edges;
• a half-scale ruler marked along at least said first straight reference edge or said base line, having a half-scale zero-point marked at the mid-point thereof, with half-scale units marked in increasing dimensions toward both ends of said first reference edge;
• a centerline marked on said tool perpendicular to said reference edges and intersecting said base line and said half-scale zero-point;
• a protractor marked on said tool with the origin thereof at the point where said centerline intersects said base line, said protractor being marked out on a generally trapezoidal-shaped layout, having a narrow top side parallel to said base line and extending in equal amounts from opposite sides of said centerline, first and second oblique sides converging toward one another from said base line to said top side at a first predetermined angle, and the intersection of said first and second oblique sides with the ends of said top side making a second predetermined angle with respect to the base line of said protractor as measured from the origin thereof;
• a hole located at the origin of said protractor to permit the passage of the point of a pencil therethrough;
• and
• a plurality of spaced holes through said tool aligned with predetermined marks of said half-scale ruler, said holes being dimensioned to permit the passage of the point of a pencil therethrough for drawing circles.