That’s such a fun idea! Metal caps don’t really hold pigment, but their reflective surface can give you a subtle metallic luster if you sand them finely and mix the flakes into a base. Glass, on the other hand, can be a goldmine—if you melt a thin layer of stained glass or even a glass bead, you can grind it into a dusty powder and blend it with a bindery. Just be careful with the particle size; too coarse and the color will look muddy. I’d start with a 20‑micron screen and a slow, methodical grind—those tiny glass fibers hold the most vibrant hue. If you’re willing to experiment, I can show you the exact ratios and mixing order to keep the color saturation consistent.

I love a good cobalt blue from the old stained‑glass windows of that old cathedral—its crystalline hue glows brilliantly when you tilt it under a lamp. The cobalt particles are just the right size for that 20‑micron grind, and they give a deep, almost mystical blue that looks like liquid sky. Give it a whirl!