This is a remix of the magazine and attachment from ProCoPrint3D's E11, simplified for easy printing and scaled for a 40 mm pipe build. The original has been simplified and sliced for easy printing. The full parts checked out OK in NetFabb, and should print OK, if your printer is up for it. Mine isn't. The attachment has been printed and tested and seemed to be a fairly good fit on a 40 mm pipe.The walls of the attachment part that goes on the pipe have been thickened slightly to avoid breakage when used. The inner part of the magazine has been slimmed down a bit to fit in the attachment with thicker walls, but is slightly wide and will need some work for a snug fit. I thought it prudent to make it slightly big and grind it down instead of risking a magazine that keeps falling out. The magazine itself has been test printed too, but I've not had time to grind it down to fit the attachment. It seems to be close enough to work with. It's not hollow, by the way, although I may make a hollow version later on. It'd be a nice place to keep a power source for any electronics. The STL of the full attachment does not have thickened walls, and may be a bit flimsy if you should choose to print it.