0.3 Now Available!
This ratchet uses several 4.5mm airgun BB's instead of plastic catches to make it stronger. It turns freely forward, and locks solid backwards, see the video. It has a 1/4" hex in the axle for screwdriver bits. You could also use it as an overrunning clutch.
I modified it from my ratchet v0.1 by making appropriately large holes in the housing for a 4.5mm BB, deepening the channels, and letting the axle fit the housing freely. The results were beyond expectation -- it's both free-spinning and strong enough to turn screws!
 Stronger six-ball version available in spragg6.stl. The case is also slightly different to accomodate it.
spragg6.stl contains all the parts you need. Fit the six BB's into the axle as you slide it into the casing, then glue on the lid.
I've included the axle separately in case you have scaling issues. The parts fit perfectly for me in Makerware with 2 shells.