[pault]

Try a keyboard running QMK firmware. You can map a single key to multiple codes depending on the length of the key press. I use caps lock as escape if released immediately, and control if held down. Putting the modifiers in the bottom corner of the keyboard was a sadistic design choice.

[Brian_K_White]

"escape if released immediately, and control if held down"

Elegant.

And I mean for those two particular modifiers with that relationship, not just the idea in general.

[imp0cat]

Or evil mode.