UPDATE: I have significantly improved this thing, the new thing is at http://www.thingiverse.com/thing:172750.
This is a cost optimized threaded tube allowing large, sturdy and relatively light-weight structures to be built.
UPDATE: I corrected a structural deficiency by creating male-male connectors and female-female tubes. The issue was at the abrupt diameter step-down between the tube and the male threaded end. Now the tube prints strong and the connectors print strong (and can now have different parameters than the tube). Tube are also now fully 150mm tall and two tube connected would be 300mm. I added _mirrored version of the new tube and connector where the threads are reversed on one end.
UPDATE2: I added hollow versions of the connector and tube and reduced the number of threads in the tube... Now a 150mm tube + connector at 2 shells and 100% infill stands at 14g.
I sliced with MakerWare 220.127.116.11 "Standard" profile with 0% infill, 2 shells, 0.2mm layer height. No raft or support are necessary.
Printed on a Replicator 2. Four tubes ended up being 51 grams so about 12.75 grams per 150mm long tube (132.33mm long minus the threaded portion).
The model is optimized for a .2mm layer height and .4mm wall thickness. The OpenSCAD file is include to allow other configurations to be generated.
There is a break-away "foot" attached to the bottom of the model to improve bed adhesion during the print. Without this feature I had several tubes break free mid-print.