We raise the problem of realisability of rings as {X, X} the ring of stable homotopy classes of self-maps of a space X. By focusing on A 2 n -polyhedra, we show that the direct sum of three endomorphism rings of abelian groups, one of which must be free, is realisable as {X, X} modulo the acyclic maps. We also show that F 3 p is not realisable in the setting of finite type A 2 n -polyhedra, for p any prime.