Ive been toying with that a lot.
do it, super easy, old saying "just keep it simple stupid"
lots of info in the diy juice section
dont have to be precise, just start w/small batches and use low % mix of flavor and adjust upward if needed.
when u get what u like then add the nic
im a cheap bas tard, for me i use about 7-10mls of flav(fruits, candy) + a few mls of menthol(diy from crystals) per 270mls of 80% vg base.
small doses of menthol is for not getting dry mouth/vapors tongue and not getting a menthol taste, more of a refesher cleaner taste and adding a slight punch to the flav profile., imo
i nuke it in the mw until its warm(timed in seconds) as it mixes better and its a fast steep method.
in less than a few minutes i have about 285-295mls of juice ready to vape for basically nada compared to retail