Three overlapping dots stenciled onto eggs beget a batch of new hues. The design pays homage to CMYK printing, which combines cyan, magenta, yellow, and "key" black to yield a spectrum. 

When you use a craft punch on vinyl, the shape's border becomes a stencil. Apply stencil to the egg, rubbing the inside edge for a good seal. Using a cotton swab, dab undiluted food coloring inside stencil; let dry before removing stencil.

To create a dark egg, make red and blue dots first, and then smooth circle stickers onto the shell. After a dip in inky-black dye, the stickers are removed.

Sources
Vinyl sheets, by C-Thru, from duall.com

Black dye, surmastore.com