There are a couple of questions.
How important is the nicotine level?
How important is the PG/VG ratio?
...
Right on Hoosier.
Because the Answers to these Two Questions can have a Profound Effect on how Easy or How Hard DIY can be for the Average DIY-er.
If a Person was willing to use a Nicotine Level that deviates Slightly from say 24mg, they could just Buy 24mg Pre-Made Nicotine Base and just add Flavoring/Sweetener. Wow... DIY just got a Whole Lot Easier. The same goes for the PG/VG Ratio.
Now if you Just Have to have Exactly 24mg at Exactly some PG/VG Ratio, then DIY becomes a Bit Harder and is going to Involve Measuring Everything to the same Exactness as the Resulting e-Liquid.
And isn't something like 24mg an Arbitrary Number Anyway? Who says that a Person has to use 24mg?
If retailers had sold e-Liquids using Non-Scalar Multiples of 2 or 3 for Nicotine Levels in the First Place, like 21.5mg, we wouldn't be having this conversation.
Don't get me Wrong. There is something to be said for a Person who wants to Measure Everything down to the +/- .01ml Level. Or for someone who has a Lot of Time and Doesn't Mind Washing a Small Array of Syringes, Pipettes, Graduated Cylinders and what not.
But I'd rather Vape a 21.5mg 67.3%VG|32.7%PG e-Liquid that was Much Easier to make.