material: PLA core: 0.8 layer height: 0.2 infill: 100% support: yes adhesion: none/skirt My printer tends to print inner diameters smaller than the design (66/65 mm), so I needed to remove about 0,5 mm on inside. The advantage though is that the surface can be made smoother with a lathe or sandpaper. The cap with the hole has no thread. If a thread is required the hole has to be bored to size and then tapped in. Or you can change the design and include the thread in the design. Tapping in a thread will probably give better result though (no leakage). A pillar/connector with longer shaft and a nut could also be a solution. Make sure the inside is smooth before fitting the hose, otherwise you might damage the rubber seal.