Another specialised set of parts for a vacuum brake reservoir using 4 inch underground drainage pipe. Builders usually have plenty of dog ends of this stuff. The parts are end caps for the pipe. I use polypipe cement to stick the ends into the pipe. One end has a 20mm hole to allow the fitting of different pipe adaptors. I use nylon or copper pipe for the brake system and a silicone rubber pipe for the actual joints. If your printer does not seal properly, then give the ends a couple of coats of undercoat to seal them.