I couldn't find a 5 gallon water jug cap that fit the Giant Primo 5 Gallon water jugs. The Giant Primo water jugs have a much thicker spout than the regular 5 gallon jugs. I saw a silicone one on Amazon and copied the design in TinkerCAD as closely as I could. I changed the dimensions to make it easier to take off and seal better for transport. I used the SainSmart TPU 95A filament.