Preparation

I'd consider this one the 200-level PM synth by Physical Audio. This one changes up algorithms and increases complexity, resulting in a greater control and more or less greater design capacity for musical sounds than Derailer. (Please see my Derailer review). Although on the surface, Preparation seems less complicated than Derailer (2 strings / bars / rattle / mass materials in Preparation vs 5 bars / connected strings in Derailer) in practice, I find that the rattle concept is more esoteric and the string dynamics deeper, along with flexible scaling of materials. Just my own experience.

That's not to say that the difficulty in control is greater with Preparation, actually I find that the opposite is true. Again, musical results are simpler with Preparation if that's the kind of sound design you're trying for.

Preparation standing on its own is an incredible PM synth experience, I feel it's essential. You can always find a starting point for an interesting new sound design option here. Those looking for something entirely different than the better known synth techniques will be stunned by this.

(I am not employed by or endorsed by PA. Just a fan of their plugins).

Cheers.