Spirograph Spirograph Spirograph is a geometric drawing toy that produces mathematical roulette curves of the variety technically known as hypotrochoids and epitrochoids. It was developed by British engineer Denys Fisher and first sold in 1965. The name has been a registered trademark of Hasbro Inc. since 1998 following purchase of the company that had acquired the Denys Fisher company. The Spirograph brand was relaunched worldwide with original product configurations in 2013 by Kahootz Toys. In 1827 English architect and engineer Peter Hubert Desvignes developed his "Speiragraph", a machine to create elaborate spiral drawings, intended to prevent bank note forgeries. The mathematician
Technical drawing tool Templates are also available for other geometric shapes such as squares and for drawing ellipses, as well as many specialized varieties for other purposes. There are also specific templates to provide user with the most common symbols in use in different branches of designing. For example, the architect templates can be used to draw different sized doors with their "opening arcs", building and equipment symbols and furniture. The templates also provide the symbols for thermal insulation. Two methods of drawing smooth curves in manual drafting are the use of French curves and flat splines (flexible curves). A French curve is