I make up a 30-60 ml batch of my base with nicotine, but no flavorings. I then put 3 ml of that base in a number of vials. I add the flavor combinations that I want to try to each vial. I use micropipettors, but before I got those I had calibrated some droppers. My big dropper was 36 drops per ml, which translates to 27.7 ul/drop or 0.028 ml/drop. A small dropper (the ones that come with TFA flavors) was 78 drops per ml, or 12.8 ul/drop.
Using that information I can add drops to the 3 ml vials of flavor, keeping a record of what I add to each. I can then test them out and pick the ones that are worth tweaking further or good as is. I can use the record to back calculate the percentages.
For example, if I added 6 big dripper drops of apple and liked that, I can figure I added 6*27.7ul = 166.2ul. That would make mytotal volume 3166.2 ul. 166.2/3166.2 * 100 = 5.2% apple. I can use 5% or 5.2% to scale up.
Of course, I use more than one flavor, but i can do the math for each flavor to come up with my recipe. This allows me to only use 3 ml of base and a minimum of nicotine for each test.
I also sometimes do this with a DIY liquid I already like. For example I had a blueberry flavor that I liked and I wanted to try adding a variety of flavors in different combinations to see what flavors could add some different nuances to it. In the case below, I put 4 ml of the blueberry eliquid into different vials and added different combinations of apple, peach, and tangerine.
