Recommend printing orientation on the side, tube facing upward away from the build plate, with supports, like so: http://i.imgur.com/jF3DygD.png. This ensures the material strength of the print such that the highest stresses are not along the layer planes. FDM Printing is an anisotropic process.
QTY 10 #6-32 press-insert nuts for plastic (McMaster 92395A113 or similar) (Assembly tip: Assemble it to the screw first, and keep threading the screw until the nut presses fully into the plastic. Keeps the brass tab from bending in the wrong direction.)
QTY 2 #6-32 x 3/4" SS hex-head screws (McMaster 92185A151 or similar)
QTY 8 #6-32 x 7/16" SS hex-head screws (McMaster 92185a163 or similar)