Magna-doodle
In 1974 a group of Japanese engineers who worked for the Pilot Pen Corporation researched and invented a way to create a dustless chalkboard that they hoped could be used in a "clean room", which, at the time, was where all computers at a business were located. After someone from the Takara Toy Company happened to see the product, he realized it would make a great toy, and thus a new children's classic was created: the Magna Doodle.
The Magna Doodle drawing board has three basic components: The drawing board, a pen, and a slide that serves as an eraser. The drawing board consists of three layers: A honeycombed plastic lattice sandwiched in between two sheets of clear semi-transparent plastic. Each cell of this honeycombed lattice contains tiny magnetic particles, such as magnetic oxides or alloys, and a thick liquid dispersion medium. The pen is plastic, with a magnet in the tip. The eraser is a long plastic piece that holds a bar magnet and fits behind the drawing board. All of these components fit into a plastic case, with a slot on the side for the pen, which is attached to the case by a string, and a groove along the bottom of the board for the eraser.
You can create a drawing on the board by running the magnetic tip of the pen along the board's surface. The magnet on the pen draws the magnetic particles to the surface, and because the particles are so fine and the dispersion medium in the cell is so thick, the particles don't fall prey to gravity and sink; rather, they remain clinging to the top layer of plastic.
The drawing remains on the board until you're ready to erase it, at which point you slide the bar magnet along the back of the board. This draws all the particles back to the bottom of the honeycomb, leaving you with a clean slate.
Although the Magna Doodle toy has been extremely popular throughout the years, you'd be pressed to find it in stores today. According to Tony Craig, Manager, New Business Development at Pilot Pen Corporation, Pilot's strategy over the years has been to manufacture the magnetic panel themselves and license the production of the completed toy to another company. In the United States, Pilot first worked with View Master-Ideal, which got bought by Tyco Toys, which got bought by Mattel. Although Pilot retained ownership of the intellectual property, the license transferred to the new company with each acquisition.
The Fisher-Price division of Mattel manufactured the Magna Doodle until 2004, when Pilot licensed it The Ohio Art Company, who is famous for their classic toy the Etch-a Sketch. According to Craig, in 2007 Pilot decided to stop making the magnetic panels because companies in China had started producing cheaper panels, which made Pilot's product unprofitable, thus ending production of the product and the relationship with Ohio Art.
Although companies like Fisher-Price market their own magnetic drawing boards, the official Magna Doodle is currently off the shelves, although if you're lucky, you may still find it at some Walgreen drug stores. Craig said Pilot is currently negotiating with companies to license out the Magna Doodle toy and hopes that it will one day be produced again.