Things You'll Need
Instructions
Cover 1/2 sheet of poster board, including the edges, with duct tape, or another waterproof tape. Laminate the poster board as an alternative to taping.
Wrap the waterproofed poster board around the water gun barrel and trigger, shaping the poster board to the gun and leaving only the handle exposed. The gun should fit snugly, but not be tight.
Apply duct tape to secure the overlapping edges of poster board. Hold the shape of the poster board in place with one hand while removing the gun with the other. Carefully staple the top and middle of the poster board to hold the shape in place, leaving the bottom undone.
Insert the gun snugly into the poster board and pinch together the slack poster board below the end of the gun barrel. Using a pair of scissors, cut away the slack poster board below the fingers at the pinch.
Staple the bottom of the poster board together to complete the holster.
Cut two equal length slits, running top to bottom, into the middle of the back of the holster. Thread a belt of choice through the slits and attach to waist.