Apparatus and method for forming a plurality of elongate members into a helical bundle. The apparatus has a plurality of bending die heads that are mounted in a circular array within a rigid housing. The bending die heads each have a pair of grooved rollers that engage the sides of the tubes to apply a bending force while allowing the tubes to move longitudinally through the bending die stock. The bending die heads can be rotated about their longitudinal axes to impart a helical twist to the tubes as they pass through the bending die stock. The apparatus also has a collet stock assembly, which consists of a collet that has a plurality of apertures equal to the number of tubes in the bundle to be formed. The collet stock is mounted to a housing that is secured to a carriage. The carriage is driven by motor and lead screw to move linearly along a track toward and away from the bending die stock while the collet is rotated at a predetermined speed to form a helical bundle.