If you were in the U.K. I could have sold you a ton of non toxic kids powder paint. Just add water and mix. I bought up 5 pallets of surplus a while back.
Because this contains the word paint! I would like to know too the answer to that question. This powder sounds good.
I have done research myself trying to find something non toxic. I have tried non toxic tempera paints and found a bit of allergen. See by the very definition of paint, it is meant to be of permanence. Any water based medium is going to need some kind of anti microbial in there as well. Formaldehyde is hidden in a lot of "non toxic" things.
Never got around to it but wanted to try milk paint. It is made with the casein protein in milk and uses natural pigments and can be purchased in powder form. I know it is a bit alkaline, how much I don't know. A little above PH 7 is okay like soap. I would try a small amount.
When the Snow White movie came out I found a little bit on what they used to make the milk bath. They mentioned titanium dioxide and a thickener on toothpaste, likely HEC or methyl methylcellulose. All cosmetic grade for the movie star. I have also pondered using a lotion base and pigmenting it to make a sort of "paint"
I feel metallic "paint" is safe. It is pigment powder mixed with oil. I used coconut. Olive or mineral is also commonly used. Oil could also be mixed with an inorganic pigment. As a example a cadmium pigment would be a very bad idea, similar to lead poisoning. Ultramarine is safe, made from clay. But in large quantities pigments can be expensive, that is why filler is used.
I have done some reading before and pondering the idea of using cosmetic ingredients to make a paint analog. Adding a polymer may help texture. When I can and it would take R&D https://www.youtube.com/watch?v=ZKBpUJbQSec
Many of the water based colors used in the leather finishing tradem before the resin emulsions are added are non toxic and have a Ph of around eight. They should be double checked for toxicity before being applied to our sensitive areas; but do not contain amounts of permanent toxic preservative as the finished products have to be safe for us to wear in contact with our skin. They are generally safer than the emulsion paints we us to decorate our homes; but there are exceptions.
Love you, too
