A dental aligner and methods and systems for manufacturing the dental aligner. A boundary contour is defined in a two-dimensional space based on an edge of a model aligner in a ruler disc. The boundary contour may be measured on a grid in which the model aligner is formed. The information pertaining to the boundary contour in the model is transferred to a flat workpiece. The boundary contour may follow the patients gingival margin. A trench is formed in the flat workpiece based on the boundary contour measured in the model aligner. The flat workpiece including the trench is deformed. Deforming the trench forms at least a portion of the edge of the dental aligner and may include a trim boundary. The aligner may be separated from the workpiece at the trim boundary. The model aligner and dental aligner may vacuum thermoformed from the same mold.
