Lord of the Rings Anduril lightsaber hilt sleeve. I designed it to fit a lightsaber so the handle slides inside. The connections are not permanent but... can be glued together, just don't glue the guard to the handle then you cannot take the lightsaber out. Hole in the side of the handle is for the placement of the lightsaber button.
Fitted for lightsaber handle dimensions: (but I would still suggest test prints for fitting)