I am looking to make a customized shooter plunger, and I think I could get a 3-D printing shop to make up whatever I could dream up for the knob, but I still would need the rod to go with it. It would seem that others have thought about this and thus someone makes a plunger with some standard machine screw on the end such that all someone would need to do is make the knob have the screw insert and then just screw the pieces together. Thanks in advance.