A method for constraining a graphical model in a CAD system, comprising the steps carried out by the CAD system: - receiving a graphic model in a CAD system, wherein the graphic model has a plurality of curves; - receiving a user selection of a symmetric constraint by the CAD system, wherein applying said symmetric constraint to an existing geometry makes existing curves or points of said geometry symmetric about a centerline; - receiving a user selection of a first curve of the graphic model by the CAD system, and designating as a first vertex of the first curve an endpoint of the first curve that is nearest to an indicated point on the first curve where said selection has been made and as a second vertex of the first curve an endpoint of the first curve that is furthest to the indicated point on the first curve; - receiving a user selection of a second curve of the graphic model by the CAD system, and designating as a first vertex of the second curve an endpoint of the second curve that is nearest to an indicated point on the second curve where said selection has been made and as a second vertex of the second curve an endpoint of the second curve that is furthest to the indicated point on the second curve; - determining a center line between the first curve and the second curve and applying the symmetric constraint between the first vertex of the first curve and the first vertex of the second curve with relation to the center line, and between the second vertex of the first curve and the second vertex of the second curve with relation to the center line; - storing and displaying the graphic model after the symmetric constraints are applied. - receiving a graphic model in a CAD system, wherein the graphic model has a plurality of curves; - receiving a user selection of a symmetric constraint by the CAD system, wherein applying said symmetric constraint to an existing geometry makes existing curves or points of said geometry symmetric about a centerline; - receiving a user selection of a first curve of the graphic model by the CAD system, and designating as a first vertex of the first curve an endpoint of the first curve that is nearest to an indicated point on the first curve where said selection has been made and as a second vertex of the first curve an endpoint of the first curve that is furthest to the indicated point on the first curve; - receiving a user selection of a second curve of the graphic model by the CAD system, and designating as a first vertex of the second curve an endpoint of the second curve that is nearest to an indicated point on the second curve where said selection has been made and as a second vertex of the second curve an endpoint of the second curve that is furthest to the indicated point on the second curve; - determining a center line between the first curve and the second curve and applying the symmetric constraint between the first vertex of the first curve and the first vertex of the second curve with relation to the center line, and between the second vertex of the first curve and the second vertex of the second curve with relation to the center line; - storing and displaying the graphic model after the symmetric constraints are applied.