I do a blended method. I have my nic and PG premixed and I used a pipette to do multiple bottles of the same volume. I then use a small pipette for single flavors from 4oz bottles and a scale for mixing recipes. I then top the bottles up with VG. I'm not that precise on the VG. I bought an automatic pipetter that I just recently had the chance to use, and I wish I had bought that a long time ago.