The technique directions read:
Using a brayer, add yellow ink to the upper portion of your glossy cardstock. Punch a circle out of a Post-it note & adhere it to the yellow portion of the glossy CS. Brayer another color over that – usually a sky or sunset color, blending the two colors together. You can leave the bottom portion plain to add a third color for the horizon. Remove the post-it circle & you have a ‘moon’.