This is a tool designed to punch a hole in auto glass. It is something that can be carried in your car and used in an accident situation to break the glass on a car window. It is designed to lock in its extended position and then retract for easy storage. This tool should only be printed with ABS or ABS Carbon fiber filament. I would recommend at least a 20% infill and 3 shells for weight and structural integrity. Once you have printed this piece, the assembly is easy and I would recommend using a high strength epoxy to affix the bottom cap. It should be used with two hands - one hand gripping the tool and the palm of the other hand on the tool's bottom. Note: I take no responsibilities for any accidents that may result in the use or misuse of this tool. The Glass Liberator is not a toy and should not be used by anyone under the age of 18 years old. I would recommend practicing with this tool by punching holes in a piece of drywall.Happy Printing, Makers!