Spagetti Stickler Punch Tool works for me
I just got this tool today upon speaking to a Dripworks person. I read one review saying it was hard to punch through the tubing. No problem here. Made of solid stainless stain so won't rust, very compact and not only punches holes but you can use it to insert barbs into lines , remove barbs and more I'm sure. Will find out more as it gets more use.