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 .