What buttons are actually useful on pendants?

I'm just designing one, thought I might do it Scalectrix fashion with buttons to select a direction and a lever to set the speed. I thought maybe click a button for single steps, but, like 5 microns? :heehee:

I left space on the mill control panel for a big knob, want the pendant to be dinky.

What would be your idea of the perfect pendant?

Feliz Navidad

Robin