Could suborthelene orthotic devices be altered using a hairdryer?

Depends on : How hot that hair dryer could get. Keep in mind when labs make these changes and are using heat guns they are usually wearing special gloves and have instruments to make these changes. Thickness of the device needs to be considered. My concern is that you dont burn yourself.

Unlikely, but...: It depends on the orthotic material. Some orthotics could be modified with the help of a small oven or the heat gun. The heat from those allows them to be corrected by re-molding them. However, the hair dryer may not be hot enough for the vast majority of the good quality materials used in the orthotic manufacturing.