I’m currently working on a sound design project for a client who is looking for a way to generate specific sorts of sounds using easy to understand controls. I started by creating a frequency modulated drone generator. The tool has a mixer with six preset pitches plus noise. I also included amplitude modulation, with sliders to control the amount, LFO, and a frequency multiplier to allow for FM synthesis effects. Here’s an audio example that illustrates the range of sounds possible with this set of fairly simple and intuitive controls.
Drone Tool Example