Orthodontic positioning devices, and related methods and systems, are disclosed for use with one or more orthodontic elastic members. The disclosed methods may comprise determining the geometries for a pair of orthodontic aligners for use as part of an orthodontic treatment plan. The geometries for the pair of orthodontic aligners may include an upper aligner with a first marking and a lower aligner with a second marking. The first marking may correspond to a position of a first hook, and the second marking may correspond to a position of a second hook. The first hook and the second hook may be configured to engage with an orthodontic elastic member so as to react a force to, for example, generate orthodontic forces on the patient's teeth.