The space between the metal sides amplifies and resonates the sound.
Sometimes merely the tone of my chanting hits the resonant frequency.
A solid metal disk does not have these properties. Without space between the sides, there is no short delay in sound waves and no chance for slight alterations to frequency to set up the layered tones that echo back and forth between the sides.
Having space in my day and in my work for ideas to bounce around, attenuate, and land on a solid surface seems more important than creating a solid mass of busy-ness. I seek a resonant frequency with the world around me. Each idea has it's own tone. As all the ideas blend, they create dissonance or harmony. But without the space, there is no blending, no bouncing. It's in quiet that I can hear In the space I build.