piston valve

This is a piston that fits in 2 in pvc for a piston valve meant for a air cannon it has a one way valve to increase performance.
To assemble it you need a: 2 in o-ring, 1 in rubber washer, a large rubber washer and a small spring.
Put the spring on the nubbin in the bottom of hole on the top then put the the solid 1 in cylinder on top of spring. Glue the washer onto to the thing that has a hole going through it then glue it into the hole push it in far enough that the marble is touching the wa