Mmm. Yes, in the sense of infusions. Just make sure anything soaked isn't poisonous. Like with the gems, make sure they don't release anything in the water that's toxic.
Personally, I wouldn't make anything to ingest beyond store bought tea. I would stick with things I could sprinkle around the house or wash with. Since it's making contact with skin, still be careful of irritation. An easy way to do it would be putting the herbs and stuff in a coffee pot.
If by elixirs you mean a sort of remedy then yes! People make remedies for lots of different things instead of buying over the counter products. Mind you, you should always listen to your doctors advice and take medication when needed. But for bug bites or face cleansers or even some mild illnesses you can find herbal remedies online!