Subtractive Approach

Isometric: This view gives a good sense of where the voids are within the cube in relation to each other. The focus is primarily on the vertical void with one end of the horizontal void in the background

2nd Isometric: A better view of the horizontal void

Perspective Elevation: You can clearly see the vertical void, as well as the secondary smaller horizontal void which runs through both the vertical and principle horizontal voids

Perspective Elevation: Looking at the opposite side the horizontal voids dominate

Immersive Perspective: Standing inside the main horizontal void

Immersive Perspective: Standing at the bottom of the vertical void looking up