I was inspired by the Customizable Cable Holder by xifle to create a captive version that did not require a wall to hold the cables in place and to show off the capabilities of a 3d printer. This rendition of the cable holder prints as a single piece with an inner barrel captive in the outer barrel and able to rotate. The cable is placed in the inner barrel and then the barrel is rotated to capture the cable in place. no wall required! the tabs that hold it to the table also include a small protrusion for a better grip on the edge. This thing is also completely customizable through the thingiverse customizer (my first customizable thing!)

http://youtu.be/hlBSWsi9f0A

The STL file is for a 5 mm diameter cable (most USB cables) and table with a 19 mm thickness, tolerance is 0.5 mm.

I printed this using a 0.35 mm nozzle with 0.5 mm tolerance in PLA on my Printrbot+. Printed slow, I had no trouble with the mechanism and it opens and closes very smoothly and the captured barrel will not come out.