Sculpting waveforms like Serge or Buchla?

I've made some wavetable synths and FM synths in MaxMSP, sorta like the ones in the tutorials. So please don't point me at them. However, I have some specific wave manipulations I'd love to do which I have a feeling I'll need to brush up on my math skills. The oscillators on my Buchla 200e have a timbre section that does things that sound like "wavefolding" or "wave multiplication" where the peaks and valleys of the waveforms are doubled up, almost like a morphing inversion (thus the folding) that happens around the zero-crossing and/or peaks. Wavetable morphs can get similar results, but I wanted a more procedural/mathematical way of achieving smooth timbre changes w/o needing a wavetable and more control over pitch than FM and AM.

Are there some objects or techniques that can get me closer to the way modular synths can shape waves? FM and wavetables are nice, but I'm looking to shape waveforms coming out of the cycle~ and other more basic waveshape objects. A buchla259~ object would be the ideal, but I kinda doubt that's even worth thinking about.