Hypocycloid prove that an epicycloid with "k" cusps moves snugly inside one with "k"+1 cusps. The evolute of a hypocycloid is an enlarged version of the hypocycloid itself, while the involute of a hypocycloid is a reduced copy of itself. The pedal of a hypocycloid with pole at the center of the hypocycloid is a rose curve. The isoptic of a hypocycloid is a hypocycloid. Curves similar to hypocyloids can be drawn with the Spirograph toy. Specifically, the Spirograph can draw hypotrochoids and epitrochoids. The Pittsburgh Steelers' logo, which is based on the Steelmark, includes three astroids (hypocycloids of four cusps).
Fisher-Price toy ever sold was "Dr. Doodle" in 1931. (The same toy, in excellent condition, would be worth a considerable amount in today's collectibles market.) In the early 1950s, Fisher-Price identified plastic as a material that could help the company incorporate longer-lasting decorations and brighter colors into its toys. "Buzzy Bee" was the first Fisher-Price toy to make use of plastic. By the end of the 1950s, Fisher-Price manufactured 39 toys incorporating plastics. During the 1960s, the Play Family (later known as Little People) product line was introduced and soon overtook the popularity of earlier toys. Herman Fisher retired at the