A method for forming a cylindrical structure by fastening an engaging member to an open end of a cylinder, including the steps of preparing an inner surface at the open end of the cylinder to provide the cylinder with a reduced thickness, providing an engaging member having a plurality of discrete recesses formed circumferentially around the periphery of the engaging member, and fitting the engaging member into the processed open end of the cylinder. The invention further comprises bending and cutting the processed open end of the cylinder around the open end of the cylinder such that plural projections project into the recesses of the engaging member. In this manner the engaging member is restricted from relative movement between the cylinder and the engaging member in both the longitudinal and rotational directions.