--> EDIT 2015-01-15: I added a doublesided version with both directions in one tool, righty tighty and lefty loosey. :-) <--
--> I saw a ton of these already but since my version is a little bit different and I put some work in it I decided to upload them anyway.
The NASA Space ratchet wrench (http://nasa3d.arc.nasa.gov/detail/wrench-mis) - first e-mailed and printed tool in space- only tightens. So I mirrored it and created the Righty Tighty Lefty Loosey set :-)
NasaWrenchDouble.stl | 1.7MB | |
NasaWrenchLeftyLoosey.stl | 1.0MB | |
NasaWrenchRightyTighty.stl | 1.0MB |