Spirograph Bruno Abakanowicz invented the Spirograph between 1881 and 1900. It was used for calculating an area delimited by curves. Drawing toys based on gears have been around since at least 1908, when "The Marvelous Wondergraph" was advertised in the Sears catalog. An article describing how to make a Wondergraph drawing machine appeared in the "Boys Mechanic" publication in 1913. The Spirograph itself was developed by the British engineer Denys Fisher, who exhibited at the 1965 Nuremberg International Toy Fair. It was subsequently produced by his company. US distribution rights were acquired by Kenner, Inc., which introduced it to the United
Technical drawing tool a device used for copying objects in an adjustable ratio of sizes. French curves are made of wood, plastic or celluloid. Some set squares also have these curves cut in the middle. French curves are used for drawing curves which cannot be drawn with compasses. A faint freehand curve is first drawn through the known points; the longest possible curve that coincides exactly with the freehand curve is then found out from the French curves. Finally, a neat continuous curve is drawn with the aid of the French curves. Rulers used in technical drawing are usually made of polystyrene.It is