Hope I instilled some curiosity. Honestly it’s not even that expensive to get started with (you can get food grade oils for about $40, then all you need is gum arabic, citric acid, sweeteners and E150 for colour, and finally vanilla for a final touch), unless you want to go real fancy with adjustable pipettes and such.

The recipes are all down to ratios of the oils, so if you do begin to experiment I recommend:

• making a big batch of the base syrup (sugar, citric acid, water, vanilla, lime juice, E150, etc.) as this doesn’t change much, but ingredients can be fine-tuned at the end
• making small batches of the “7X” mix (the Cube-Cola recipe actually calls for minuscule amounts, we’re talking down to 0.05ml, so use that as a starting point and shift the ratios for the Pemberton recipe), mixing it with the gum arabic (again use the Cube-Cola recipe for ratios, this is basically to make the oils water soluble without using alcohol)
• taste test the batches, and make sure you take very strict notes (scientific method comes into play, as you will be most likely mixing 6-8 variants like I did, keeping meticulous notes as to what you changed compared to previous recipes helps honing in the right flavour)
• start with pure white crystal sugar for sweetening - various sweeteners have after-tastes or the commercial variants have additives that cause foaming or separation, so before you go sugar-free, tune in the flavour you want, then experiment with sweeteners.
• if you can get some, try phosphoric acid instead of citric acid - much more sour and has lesser health effects, meaning you can use 1/10-1/20 as much.
• neroli oil is kinda spenny but worth the money given how little you can put into the mix and still have a strong effect on the flavour.
• Do NOT go overboard with the lavender oil. In fact go super duper careful with it because one minor spill and it WILL stick around on your clothes, skin, mouth, kitchen tiles, everything, for weeks.
• same goes for cassia oil. Be very, very, very careful, unless you want to smell like you’re sticking entire cinnamon sticks up your arse.
• an adjustable pipette costs about $30, but is immensely helpful. I ended up getting a 1ml with 0.001ml stepping and a 5ml with 0.025ml stepping. Tips are cheap, and easily connected/ejected as these pipettes are designed for lab use, so you can ideally dispose of the tips without contaminating anything else. Which is important because of the previous two points.
• Mix in a tall glass. For the gum arabic mixture and beyond I recommend using a small motorised milk frother (it’s like, $5), as that fucker needs lots of work to dissolve.
• careful with heat exposure. The gum arabic base (gum arabic + water mixture before adding the oils), and the base syrup (water and sugar) can take the heat, but the flavourings - let it be the vanilla, the 7x mix, or even the caffeine citrate - can’t. Make sure that everything is room temp when mixing the latter or dealing with a mixture containing them. I once overheated the 7X mix with the milk frother by accident, and it turned out to be the most disgusting, bitterest juice straight from Satan’s asshole.

I think I’ve gotten all the generic advice down I can. I do have a bunch of notes tucked away somewhere, I’ll try to find them!