I took the original skull from (www.thingiverse.com/thing:906562) and removed the top and the bottom so that i can test single line and double line walls with no supports and no bed adhesion.

The end results are pretty awesome and i really think it is something that everyone will enjoy.

In Cura, to remove the top and the bottom of the skull, set the top and bottom layer settings to 0 layers.

If you want the top gone and only print the bottom closed, then set the top layers to 0 and the bottom layers to how ever many you want.