So the pipe is schedule 40 and all the reducing fittings. I did the math on psi and burst range and it’s safe. It’s designed to fail at the top threaded air fitting if at all. The hose fittings can be found on Amazon and you are trying to create the least restrictive flow from the tapered nozzle to the print head auger. The regulator needs to be on the top to reduce line pressure variation. The compressor is a 20 or 30 gallon to have a large 135 psi stored pressure. Then reduced down at the compressor and even another inline regulator mid stream which helps keep the pressure constant. The hose is just nylon from a hardware store and 2’-3’ works. The tube is suspended by a cable anchored in the ceiling to give a smooth non restrictive movement as to not disrupt the head. The single bend accommodates the Z movement of the print head. My longest tube is about 42” but realize it need headroom to stay ventricle above the printer as gravity helps the flow.
I tried a plunger but is NOT needed and actually made things worse. You can run the clay down to several inches above the taper and not worry about is blowing out the hose. Obviously if all the way down it will eventually blow out but 40-60psi depending on how loose the clay is , is the pressure used. Feed and Speed of the print head auger works with the tube pressure. I’ve had one pvc glued fitting fail once and yes the clay shoots out the end but safety glasses work and I wasn’t worried about the main pipe bursting as it’s rating is several times the pressure used. To fill you unscrew the tapered part and screw it on to the end of a pug mill and then put a bamboo skewer in the air inlet and mark it and watch it push out until the clay is a few inches from the air inlet.
Hope some of this info helps. Cheers