Yeah but I need recipes. I'm not much of a great experimenter in some such cases, and like a good starting point.
Hmm... making syrups. I don't think I could build a custom system for syrup deployment, but... hmm. I bet I could use the pressure cooker to cook ginger root and infuse it into water without vaporizing much off. Likewise vanillas or root beers (if I could get the root--you can't, it's illegal because you can make MDMA from the safrole, so says Google).
No idea where I'd go with Dr Pepper clone. Technically these are called "Pepper" drinks or something; Dr Pepper Co has been taken to court for monopoly over "Pepper flavored drinks" that are "Technically not Colas".
safrole is a carcinogen which is why you can no longer use it in commercial soda. you can however grow your own and it is totally legal to grow, harvest, own, cook with, eat, drink, fondle. There are also de-carcinogenated versions of extract available. However look into Wintergreen, Licorice root, burdock root, birch twigs, etc. many many herbs can make a nice soda. Ginseng makes a nice one two. Maple syrup, vanilla and some wintergreen would make a tasty cream soda I bet.