Abstract: A tool and method is provided for attaching an endcap to a medical instrument such as an endoscope tip, wherein the endcap includes an elastically deformable, endcap opening having an unexpanded diameter that is smaller than the diameter of the instrument tip and an expanded diameter that is greater than the diameter of the instrument tip. The tool has a first component adapted to hold the endcap and to receive the instrument tip and a second component operatively associated with the first component and movable with respect to the first component, wherein the second component is adapted to apply a force to the first component. The endcap opening may be elastically deformed to have the expanded diameter prior to positioning the endcap at a desired longitudinal location and angular orientation with respect to the endoscope tip.