This is a remix of https://www.thingiverse.com/thing:1082987 by RentaPrinter.
I had lots of problems printing the original pistons - probably due to my inexperience. I found that where the screw goes down into the base my prints would snap off. So I modified these files so that the bottom of the screw ends flush with the top of the base. I'm sure someone will now tell me there is a way I could have fixed this in S3D :-)