A guy I know makes his own .055 by getting a spool of 1/16" soft brass wire and straightening it (and work-hardening it). He connects one end to a pole and the other end to the bumper of his car. He lets the car roll gently away from the post until the wire goes "twang", at which point it is (1) very straight, (2) very hard and (3) somewhat less than .0625" (closer to .055"). You can buy .0625" (16 gauge) brass wire at almost any craft supplier.