I did a little brush-tapping but my results were much less consistent than I expected. Now I'm looking for an extremely fine mesh screen to make a "sifter". If you've ever seen how a sifter spreads powdered sugar on a baked desert you'll understand the idea. It releases the powder very evenly and where you want it.

I figure I can form the mesh into a 1/4" cup and sift it right over the powder paint bottle.