Where can I get powdered tempera paint? - Model Railroader Magazine

Most likely at a School Supply store. It used in our primary schools to teach kids how to make a mess on a piece of paper. That way the child can take it home and put the "art work" up on the parents refrigerators, attached with souvenir magnets.

From: The MadSci Network
Powdered paint formulas are really just paint formulas without the liquid ingredient, namely the water. Typical formulas contain the following solid ingredients:

"pigment" (to provide the color)
"clay" (thickens the paint when water is added)
"binder" (a polymer that forms a film when it dries, typically corn starch or dextrin)
"preservative" (powder that will destroy any bacteria or mold that isintroduced)
"filler" (extra solid stuff added to give the paint some volume and does not serve any particular purpose otherwise, such as calcium carbonate or another clay, etc.)

Here are a few links to powderd tempra paints.
Here is a link to Black, the other colors available are at the bottom of this page.

I hope these were helpful.

Jerry