If you do pretty much the same thing all the time, it can be real easy.
Once I got started, I realized all my juice was pretty much around 6% flavoring. So I no longer even measure anything. I mark the 30ml bottle with a sharpie to where it is 8.75 nic (14mg) and fill to there with nic. I'd measured my flavorings to find that 1ml = about 50 drops. So then I just put in my 90 drops of flavoring. Then fill to the top with VG. Done. No beakers, syringes, scales, and takes a min or two to make 30 ml.