CONCEPT 2: THE SPRING THAT ROCKS THE CRADLE
This desktop toy is based upon the toy/educational device known as a Newton's Cradle. While the Newton's Cradle demonstrates transference of momentum and conversion of potential energy to kinetic energy, this toy incorporates springs between the balls as seen in the following sketch. Adding these springs allows for the conversion of potential energy to stored spring energy. Also, by plucking any of the three balls, a wave can be generated in a front to back fashion or a side-to-side oscillation can be established. The direction of motion depends only on the direction in which the first ball is tugged.
This toy should be especially cheap to construct with a majority of the cost stemming from the four central spring segments used. Just like the see slide, this toy is meant for desktop play and if that is kept in mind then it should be pretty durable. To avoid a choking hazard (in case the child is able to pull off one of the balls), this should be targeted for kids who are at least 5 years old.
Author: Rohit Rao (rur@andrew.cmu.edu)