A drafting instrument capable of measuring the area of a graphically represented planar region is known as the planimeter. This mod features a coke can used to make the planimeter. Another version of homemade planimeter can be made using a plastic spoon.

To use the homemade instrument, the total rotation of the can is made proportional to the area. The pointer is moved round the shape to be measured as it projects horizontally from the right-hand side of the can. The can is made to rotate by exactly the same amount by moving the pointer round any one of the 4 different colored shapes. Both hands are used in linkage moving.