The present invention is directed to a method of fabricating a successive set of patterns representing incremental stages of an orthodontic treatment plan, and then sending all or a portion of the successive patterns at the same time to the dentist. The dentist is provided with a vacuum machine for thermoforming a set of aligners as negative impressions of the positive teeth patterns. A polymeric sheet is inserted into a vacuum forming machine and sucked down over the positive pattern, forming a polymeric shell with cavities shaped to receive the teeth and resiliently bias or reposition at least some of the teeth into alignment with the aligner cavities. When the aligner is formed and while still on the stereolithographic plastic pattern, excess portions of the aligner polymeric material are trimmed using manual tools and/or a laser cutting machine.
