I made a 3D visualization of this a few weeks ago:

https://dahlend.github.io/the_belt.html

This includes about 1.3 million known asteroids (most of the known ones), so the page is like 45mb. Consider yourself warned.

This is a plot of semi major axis, orbital eccentricity, and inclination of the orbit. The blobs are collisional groups, where a bigger rock(s) got smashed into 'families' of asteroids. Color is by the absolute magnitude H, which is a normalized, log scaled, brightness measurement. Typically smaller H means larger object.

You can see the Kirkwood gaps clearly along one axis, but as you move around you can see more complex orbital resonances. These resonances pump energy into or out of the orbit of the asteroid, causing them to leave the resonance after some time, depleting the region of phase space.

Source: I do solar system simulations for my PhD work.