This is a lovely effect using the happy mask from Stampin up. I used a variety of ink pads to achieve a rainbow effect. Secure the mask in place with low tack tape and the. Using the sponge daubers ink through the mask in a variety of different colours to get rainbow effect.
By adding a birthday and too you from the Endless Wishes stamp set it makes a lovely birthday card.
For all Stampin Up products use the link above and me Jane Allmark as your demonstrator of choice.