Multi=purpose ruler used in industrial building design

摘要

A flat, graduated 20-cm ruler (1), for use in draughtsmanship, incorporates additional perforated strips (2, 3, 4, 5) which are attached and hinged to its underside by adhesive tape or glue. The additional strips are hinged to the ruler and to one another so that the ruler acts as a straight edge for the perforations in one strip and that strip acts as a straight edge for the perforations in the next one. The strips have perforations of different sizes and are made from a semirigid transparent material in different colours.