I haven’t looked at full voxel or marching cube rendering - my suspicion is that this would be beyond the limits of MakeCode Arcade hardware devices (though I’d be happy to be proven wrong), but seems doable on a sufficiently fast machine using the emulator. The new native polygon-drawing functions should be a big help, I didn’t have those back when working on my renderer.
The closest I got to voxels was a 2.5D height field implementation in Fire Rescue Chopper, but that’s of course far simpler to implement.