The disclosure describes a flexible-rigid hybrid design for an endoscope and attachment mechanisms for removably coupling and decoupling the endoscope to a handle portion and/or a tool portion of a variety of different instruments. Some implementations describe designs for instruments that may be coupled to the flexible-rigid endoscope described herein or other endoscopes. Such instruments may include sinus and laryngeal forceps, a laryngeal syringe gun, an endoscopic Eustachian tube balloon dilator, an endoscopic tracheal dilator, and an endoscopic trans-oral esophageal balloon dilator. Some implementations describe an endoscope that may be removably coupled to a portable control box using a connector cable.