Bill's Magic Vapor (ex-commercial eliquid maker, well-known and loved ECF member, a wealth of info. on DIY, etc.) was someone I learned a lot from in my early days of DIY. I tried many of his recipes, read his blog (there's a wealth of info. in it by the way), followed him on the TFA thread, etc. He's not been active for awhile now on ECF, but I still regularly use some of his techniques, hints & suggestions, etc. and I refer back to a file I have saved with a bunch of his "stuff".
One of his methods used to easily make various eliquid recipes was to make what he called "bases". (I've always thought he probably used these as a commercial mixer.) Specific flavorings are mixed to make each specific "base" type. That 1 base could then be turned into any number of different eliquids of that "type"...by simply adding a different single primary flavoring to the base. I'm thinking those "bases" were probably a type of "stone", as people are calling them nowadays.
Here are a few of them below and his recommendations for using each one. All flavorings are TFA unless otherwise noted. He is/was a high total flavoring % guy. But it's easy to cut that down. At first, I made them as written, but I've found that cutting each by 1/2 is still flavorful enough, for me.
For several years, I made 120mL or larger bottles of several of his bases. I'd then just pull off some of the "base" and add a single Primary flavoring to make my individual recipes. Worked like a charm for me.
Custard - Make a custard eliquid by adding any single flavoring to this mix. You just need to work out the % for that flavoring. It's usually going to be between about 7-13%. Starting at no more than 7% for stronger flavorings would be best.
Cotton Candy 7%
Vanilla Custard 6%
Bavarian Cream 6%
Creams - This cream recipe is great with fruits and just about anything else. Add a single primary flavor ingredient to this, in the 10-15% range. I would start at 10% and increase until you find the sweet spot.
Sweet Cream - 5%
Vanilla Swirl - 5%
Hazelnut - 2-3%
Honey - 3%
Sweetener - 2-3%
Vanilla Milkshake Base - Add about 5% of any fruit flavoring to make that flavor milkshake.
VBIC - 10%
Marshmallow - 5%
French Vanilla Deluxe - 4%
Sweetener - 3%
Dulce de Leche - 2%
Koolada - 1%
He also has bases for cobbler, danish, and pies.