A fin forming device folds fin material into a plurality of corrugations by creating a fold radius at each fold. The device comprises a substantially rectangular plane of metal having a front side, and an opposing back side. The perimeter of the plane is defined by a top edge which is applied to the fin material to form the fold radius, a bottom edge, and a pair of opposing side edges. Initially, each of the edges has a substantially similar thickness. An angled surface is created on at least one side of the plane, commencing in an interior area of the plane below the top edge of the plane and terminating at the top edge of the plane. This creates an angled blade surface along at least a portion of the top edge of the plane. The angled blade surface has a narrower thickness than the initial edge thickness.