Only a few algorithms are known which could construct magic squares of any even order (n=4,6,8,...). Usually most of the algorithms use the symmetry of double-even and the asymmetry of the single-even squares, so that these methods will only work for a special group of magic squares.
But there are also some algorithms to create magic squares for all even orders. The most famous algorithm is related to Devedec, who found a rather complicated pattern. The second algorithm was published as a computer program. The author of the program mentioned that he found this algorithm somewhere, but didn't cite the original author.