Abstract: An apparatus is provided for resolving a collision between a first face and a second face of a sheet metal part represented by a 3-D model. The faces collide with one another when a 2-D model of a flat sheet metal part, designed on a CAD system, is folded into the 3-D model displayed on the CAD system. The apparatus comprises a detecting means, an analyzing means and an eliminating means. The detecting means is for detecting each collision between the faces which become adjacent in association with folding the 2-D model into the 3-D model. The eliminating means is for eliminating the collision by designing a 2-D model of a modified flat sheet metal part which can be folded without causing the collision.