Was always my first tweak to a new machine - such an obvious change. Moving to a split keyboard gave me three keys at each thumb - the same kind of realization. We have two thumbs that most keyboards map to a single space bar. The thumb is a really solid finger for modifiers.

Another nice thing about a custom keyboard is not needing to map the keys - it's in the firmware.

I do this but better:

- caps + key = control + key

- tap caps = escape

- caps + space + key = ctrl, opt, cmd + key

All done in my keyboard firmware.

This is trivial to map on QMK/ZMK mechanical keyboards too, using mod-tap: https://docs.qmk.fm/mod_tap

Caps Lock <—> Esc should honestly be standardized on keyboards. Esc is used pretty often in my experience while Caps Lock, being modal, only gets the occasional press even when used.