Warning!!! This is ridiculously large! I modeled in in meters to avoid SketchUp's small face problem!
This is a quick and dirty model of a bolt and the "negative space" surrounding it. The negative space is what would need to be removed from the rest of the model in order to actually use this bolt. The negative space around the bolt body has a slightly larger diameter while the negative space around the bolt head has a significantly larger diameter in order to use a socket to turn the bolt! Since this was created to talk about negative space in a forum post, I haven't bothered to detail the other end of the bolt - in real life, access for a nut/washer would need to be included in the negative space.
I have intentionally violated one of the rules of component creation I try to follow: Keep the component in a single layer. I've left additional layers in the component to aid in understanding what is going on.
With all parts visible, you will see some z-fighting when you look at this. That is expected as the face where the negative space widens is in the same plane as the bottom of the bolt head.