This is a vacuum hose adapter that allows a Shop-Vac 45mm hose to connect to a Kent CNC dust collector which has a 4" diameter vacuum port.
The Kent CNC dust collector I just purchased has a threaded 4" vacuum hose connection, so this has an interior thread on the 4" section that fits directly onto it very snugly.
The other end allows a push-fit onto the 1.75" hose from my Shop-Vac.
I largely work in SolidWorks these days, so that's the CAD file format uploaded here.
I printed this on my Replicator at 0.25mm layer height. I oriented it vertically with the 4" section on the build platform.
The loft and threads were designed at a gradual enough angle to be printed without support material. If you slice thicker than 0.25mm the push-fit ridges on the 1.75" end might give you trouble.
The instance pictured here was printed with no raft, no support, 10% infill on a 120C HBP in black ABS. I had no issues with warping or lack of sticking and no strings in the overhangs or threads.
I've had much more success printing a variety of things since leveling my HBP with http://www.thingiverse.com/thing:23257 from phineasjw. It's brilliant.