4volt design with a small gap

I have seen how many people added to lists or collections, you should know the original was here: http://www.thingiverse.com/thing:137367

This is just a remake with a slight improvement

Because all printers have not such precission to make the hole just tight enought to let it get through, this is why at the design there is a small gap, wich it was not included. It actually works better, but

the 3D file is not a clean one... but because I also show how slic3r works,

on Pro tip, whe