To level the bed I had to turn the screw from above and hold the lower wing nut with the other hand, or hold the screw from above and turn the wing nut below.
With this little part you will only need one hand to level the bed of your 3D printer.
Print this litte part 4 times, put nuts in and switch them against your wing nuts. To level your bed you only have to turn the screw from above.
See all the other things I created at: http://www.thingiverse.com/TheRealNapalm/collections/napalms-stuff
If you like my work, consider using the TIP DESIGNER-button on the left and push the Like-button above. Thank you.
I used a 0.4mm nozzle and a hight of 0.2mm