I assume you mean how is an AR-15 rifle made, so here we go: The AR-15 is based on the 7.62 mm AR-10, designed by Eugene Stoner of the Fairchild ArmaLite corporation.  Th…e AR-15 was developed as a lighter, 5.56 mm version of the AR-10. The "AR" in AR-15 comes from the ArmaLite name. ArmaLite's AR-1, AR-5, and some subsequent models were bolt action rifles, the AR-7 a semiautomatic survival rifle and there are shotguns and pistols whose model numbers include the "AR" prefix.  .
1973 Colt AR-15 SP1 rifle with 'slab side' upper receiver (no forward assist) and original Colt 20 round box magazine.
ArmaLite sold its rights to the AR-10 and AR-15 to Colt in 1959. After a tour by Colt of the Far East, the first sale of AR-15s were made to Malaysia on 30 September 1959 with Colt's manufacture of their first 300 AR-15s in December 1959.  Colt marketed the AR-15 rifle to various military services around the world, including the U.S. Navy, Air Force, Army, and Marine Corps. The AR-15 was eventually adopted by the United States military under the designation M16. However, Colt continued to use the AR-15 trademark for its semi-automatic variants (AR-15, AR-15A2) which were marketed to civilian and law-enforcement customers. The original AR-15 was a very lightweight weapon, weighing less than 6 pounds with empty magazine, though later heavy-barrel versions of the civilian AR-15 can weigh upwards of 8.5 lbs.  Today the AR-15 and its variations are manufactured by many companies and have captured the affection of sport shooters and police forces around the world due to their accuracy and modularity. (Please refer to the M16 for more history on the development and evolution of the AR-15 and derivatives.) -Courtesy of Wikipedia.org (MORE)