Rolling ruler

A rolling ruler is a ruler that contains a cylinder much like a rolling pin inside, thereby enabling it to "roll" along a sheet of paper or other surface where it is being used. A rolling ruler can draw straight, parallel lines, and also has other instruments included, enabling it to do the jobs of a protractor and compass.^[1][2]

References

1. ^ Jack E. Ingels (2003). "Using Drawing Instruments". Landscaping: Principles and Practices. Cengage Learning. pp. 11. ISBN 1401834108. 
2. ^ Jim Tolpin (2007). "drawing techniques". Measure Twice, Cut Once. Popular Woodworking Books. pp. 24. ISBN 155870809X.