To create this card you need four things: ink, paper, stamping tool and the VO Dots Stamp Set.
A stamping tool makes life so much easier no matter what you are stamping but especially so when stamping with this overlay technique but no worries, you can achieve this with an acrylic block too.
Here's a close-up that really explains how to do this. Simply stamp the dot overlaying each color as you move your paper when using a stamping tool. The stamping tool has the gridlines that allow you to align your paper and keep it straight while positioning it.
Curious about other products used to create this card? Then jump over to The Relativity of Paper for a complete supply list.