It's not plane-fillingness, but fractalness of the inputs that makes the DFTs look interesting. So I'd experiment with other L-space system curves. A fractal ha

It's not plane-fillingness, but fractalness of the inputs that makes the DFTs look interesting. So I'd experiment with other L-space system curves. A fractal has some periodicity that appears as bright lines on DFT, and when you add an extra level of recursion, the original periodicity remains and it gets supplemented with its harmonics. I'd also try to interpret a diagonal scan of the DFT images as a sound waveform, probably scaled down to fit it into the audible range. There's also a related so-called Radon transform that would make the DFT images more roundish.