Orientable Thumbscrews
thingiverse
To make my Makebot platform level, I use thumbscrews (http://www.thingiverse.com/thing:13778) but constantly turned them in the wrong direction, especially with my left hand. So, I modified the design by replacing the symmetric teeth with two non-symmetric shapes for easy identification of rotation direction. You can download and print orientable_thumbscrew.stl, which has a nut slot tolerance designed for my Makerbot. If you have a well-calibrated 3D printer, you might need to scale the model or edit the source file, orientable_thumbscrew.skp, available on this page, drawn with Google Sketch Up.
With this file you will be able to print Orientable Thumbscrews with your 3D printer. Click on the button and save the file on your computer to work, edit or customize your design. You can also find more 3D designs for printers on Orientable Thumbscrews.