New, robust and efficient design of protractor.


The product design described here is an attempt to redesign the protractor which is used to draw angles on a plane surface. The new design is an attempt to replace the old product with a new one, which is more robust in terms of its design and is expected to bring a change in the way the product functions. The design has evolved over a long period of brainstorming and understanding the necessity of redesigning the old product. The important objective is to minimize the time of functioning of the protractor. The design was finalized by performing iterative optimization. The overall size is kept small enough to fit inside any geometry box, the thickness of each layer is kept 1.5 mm so that the total mass should be less and also provides adequate strength to the protractor. The designed product was then 3D printed to find any possible flaws in the design, and was subjected to redesign and then again 3D printing.


The design requirements we considered for designing the protractor were based on certain points so as to make it better than the existing design without hampering the experience of the protractor. They were:

a) Reduce time of operation
b) To make product multifunctional
c) More accurate in its function
d) Easy in operation
e) Flexible design
f) More durable design


Main Body Design

The main body design consists of three layers of semicircular shaped structures. The inner diameter of the middle layer is kept less so that it can provide a cavity between upper and lower layers to accommodate the movement of pointer freely. In the lower part a slot is provided to attach a roller. The function of the roller is to draw parallel lines similar to roller scales easily available in market. But in this product the primary function of roller is to reduce the error produced due to hinge in drawing the angle, whereas drawing parallel lines is a secondary function.

Pointer Design

The thickness of pointer is kept less than the gap in between upper and lower layers of the main body for smooth movement of the pointer. The thickness is kept larger in the middle region to fill the gap between the pointer and the plane on which the angle is drawn.


The error produced due to hinge can be removed by using the roller. The line drawn along the pointer can be matched with the horizontal line by rolling the protractor upwards and then by drawing the line(dotted line in fig.) along the edge of main body of the protractor. The use of roller can also replace the requirement of buying a roller scale separately.

Design Specifications

The main body of the protractor is supposed to made of clear transparent plastic, which must be hard and durable. The use of more material as compared to a conventional protractor increases its cost, but the greater thickness provides a much better strength to it.