Silly Putty is a toy based on silicone polymers which display unusual physical properties. It bounces, but breaks when given a sharp blow and can also flow like a liquid. It was originally created by accident during research into potential rubber substitutes for use by the United States in World War II.
After its success as a toy, other uses were found. In the home, it can be used to remove substances such as dirt, lint, pet hair, or ink from various surfaces.
The material's unique properties have found niche use in medical and scientific applications. Physical therapists use it for rehabilitative therapy of hand injuries.
Slinkys, from the Swedish word meaning "a serpentine or undulating form," are springs with zero compression or tension.
It was discovered in 1943 by Richard James, who was working to design a spring for the U.S. Navy that would keep sensitive ship-board insturments steady while at sea; James was amused by the way the spring "walked" down elevations and invented toys from these springs which were first sold in 1945.
Slinkys can perform a number of tricks, including travelling down a flight of steps end-over-end as it stretches and re-forms itself with the aid of gravity and its own momentum, or appear to levitate for a period of time after it has been dropped.