KUSAN SAUCER LAUNCHER
Kusan was a toy company with offices in Nashville and a plant in Franklin, TN. They were best known for their toy trains (collector items today), but were also big in the toy gun and yo-yo markets.
As the market for trains and guns faded in the early 1960s, Kusan moved into injection molded plastic toys. By 1973, their advertising was filled with an array of plastic toys. Obviously, the Kusan disc was not a hot item as there is no record of its age, but my best guess would be mid-70s.
It was sold as part of Kusan's Saucer Launcher, the other parts being a second 4" diameter red Mini and a yellow launcher similar to a Jai alai cesta. The bottom of the Minis are embossed with "Kusan, Inc. Nashville, Tenn", "No. 300" and a mold number.