The pencils I plan on getting, Faber-Castell's Polychromos, are certified ASTM Non-Toxic, the cedar casings are made from their own farmed cedars, and the oil-based cores are vegan, for those who care about that sort of thing. I try my best to be mindful of what I use, and how safe it is. However, I leave the making of my art supplies to the professionals.
I've come to accept that everything I do will make a 'footprint' on Earth. I still however try to use safe materials if possible and make sure to utilize health/safety precautions as needed. I've seen fellow artists do the worst to the environment and their health and I'm not about to follow suit. I specifically avoid varsols, high-toxin paints, etc.
Most of what I utilize is pretty low-toxic to me and my environment, esp if disposed of properly. I work with pencils, clays(Plym/PaprCly), paints (WC/Acrylc), and re-use my trash/clippings for dioramas. Old/used paint is dried before tossing in the garbage (not the drain!). I also utilize my computer for art, and dispose of any broken/old tech at special deposit sites.
Last spring I experimented a little with aerosols to make realistic trees for a forest diorama. It was a short-term project, and they turned out beautifully, but I haven't made any that way since - I'm still looking into a safer/better way to make them.
As for making my own paints...I've tried teas/coffees and am not a fan of them. The effort/time it takes to clean, prepare, cook/dry, etc is too much for me to handle, it still takes a lot of energy to cook/store, and I feel is safer to just buy what I need. I'm also only on Earth a short time; I'm here to make art, not an herbarium.
I've always regarded art as one of those pursuits that involves hazardous and environmentally unfriendly materials by it's very nature, and just roll with it.
Personally, I detest the idea of compromising my art through concern for the environment; if there was no difference in performance with home-mixed and 'eco' paints then I'd have no problem, but whenever I see some eco artist's work it looks like it's painted with mud. In terms of less toxicity I use Daler Rowney System 3 acrylics, which use entirely artificial pigments, so no toxic metals and stuff like that, although they are obviously made of plastic, and so are certainly not environmentally friendly.
Something to consider: most everyday activities are a lot more harmful to the environment than art. If you drive a car then there's really no point at all in worrying about using ecologically friendly art materials.
Making your own paints isn't any more environmentally friendly than buying paint from the store. But you can educate yourself about common pigments, and avoid buying heavy metal pigments when you can.
And please take notice: A "non-toxic" label has nothing to do with whether or not something is environmentally friendly. It just means that it isn't very harmful to humans. They can often still fuck up soil and water. Likewise, a lot of things that could make you sick are completely fine for the environment. What you want to look for instead are things that use natural materials--particularly minerals and organic compounds. These can usually be accepted back into the environment.
Blood and coffee, Ive heard are used. You could do some water color stuff with juice, coffee, food coloring, etc.
Plus also trash if your a sculpture artist.
I don't think most of the toxicity matters, but only oils I was concern about, because there is more time to take care of oils rather then acrylics. Acrylics tend to be less toxic, unless you get the highest grade ones. I realize this, because I bought a gesso from blick and phew, that gesso was toxic smelling.
But most paints you get, will have some sort of dangerous chemicals and some sort of danger. I don't know if its totally unadvoidable.
I've messed around with making oak gall ink, but just for fun, not because of any concern with toxicity or eco-friendliness. Some years are better than others for oak galls. You can buy them online, but once you've had oak galls shipped to you from overseas it seems like you've gotten kind of far away from the point. You can also make your own charcoal out of willow sticks, etc. You can also get pigment for black ink this way.
And you can make pens out of quills and reeds! Fun!