I made those models without a lather at all - like a beginner. For one of the model (double acting) I took a cylinder from the gas cylinder for a car door than i did as it is shown at photos. Another the cylinders are made from the gun cartage (caliber 28) The pump is also made from the details bought in a car shop. the valve piston i made round by an ordinary driller. The description i took from the USSR model books for teenagers.