Can you mix plaster with a metallic paint to get venetian metallic ?

I could not locate any firm answers when I googled your question. So, I would try adding the metallic paint to a small portion of your plaster and applying it to a poster board or small piece of dry wall and see if you come up with the look you want. If so, then you'll know it works and will just create your own formula with the appropriate ratio of ingredients. It seems to me it would work or you might be able to add "powder metallic" that can be found at craft stores. Get creative and let us know how your project turns out by posting a pic here & how you finally did the project. Good luck to you!

Try a little sample of it and see.