I’m interested in negative space, which could be easily ignored but could be very useful in some cases.

There are a lot of smart graphic designs using the notions of  negative spaces:

I want to make a 3D object to play with the negative space.

Because I’ve got a wood block like this:

So I think I can subtract the material from the negative space and get the shape I want.

Below are the cutting processes on the machine called 4 axis mill:

Finally I got this cylinder, which was created from the negative space of the block: