Magna Doodle is a children's magnetic drawing toy, consisting of a magnetic drawing board, a pen, and a few magnet shapes. It was invented in 1974 and over forty million have been sold to date. In Friends, a Magna Doodle is seen hanging on the door in Chandler and Joey's apartment, first appearing in "The One With The Hypnosis Tape" (S3E18). Different drawings appeared on it in each episode. The Magna Doodle was taken with Joey when he went to Hollywood, in the spin-off, Joey.
The key element of the Magna Doodle is the magnetophoretic display panel. Each honeycombed cell of the lattice is filled with a thick liquid filled with tiny magnetic particles. The middle layer is latticed so that there is always an even distribution of the magnetic particles across the entire surface of the display. The liquid is designed so that the particles can be pulled through the liquid in response to magnetic force applied by the pen or eraser, but not due to gravity.
The Magna Doodle was produced by Tyco until 1998 when most of Tyco's toys were sold to Fisher-Price. The Magna Doodle is currently produced by The Ohio Art Company and used to be distributed in the United Kingdom by Fisher-Price. Fisher-Price has discontinued the Magna Doodle and have produced their own alternative, the Doodle Pro. It is still available in the UK, from the distribution company Megatel LTD.
- How Magna Doodle Works (HowStuffWorks.com)