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).
Stickle Bricks Stickle Bricks Stickle Bricks are a construction toy primarily intended for toddlers invented by Denys Fisher in 1969. The brand is owned by Hasbro, and as of 2016 is sub-licensed to Flair Leisure Products plc. An individual stickle brick is a colourful plastic shape a few centimeters long which has a "brush" of small plastic "fingers" on one or more surfaces. The fingers of adjacent stickle bricks can interlock, allowing them to be joined in various ways. Standard sets of stickle bricks contain triangular, square and rectangular pieces. Many recent sets also include other types of pieces such as heads,