Currently to build things fast you have to enter Build mode and this then disallows normal actions to happen properly :/
(Maybe there is way for this or maybe I am wrong)
But I think it'd be neat if you could while Ctrl is held down, build units based off of a preset list of Hotkeys. G for Generator , M for mex etc, where these are then can be edited to whatever a person prefers.
I'm not sure if there already exists a way to do this, but i always found build mode to clunky to use :/
I think this could be easily achieved by instead of having Build mode as "B enter Esc leave" Setting default as simply Holding down B or holding down another Key which is set.
Edit; This should probably been in the suggestions subforum... My bad