The method includes producing a stack of coil loops from a continuous electrical conductor, the coil loops having two parallel straight side portions and two opposite curved end portions connecting the ends of the side portions. A length of each coil loop in the stack of coil loops decreases, whereby a staggered end portion is formed at each end of the stack of coil elements. The end portion of the stack of coil loops is bent into a predetermined bending angle, whereby the staggering has been determined so that an outer end of the end portion of the stack of coil loops is substantially straight when the stack of coil loops is bent into the predetermined bending angle.