This card is something I just "tried" and I love the marble look!
I started with Glossy White Card Stock and Reinkers (this only works with the Glossy CS), Cut the CS to the sizes you need and then put small drops of reinkers randomly around the CS, using your Brayer roll back and forth changing directions all the time (you don't have to press to hard), keep rolling and adding small drops of reinker until you like what you get! IT'S THAT EASY : )!!
I used Melon Mambo and Rich Razzleberry with the stamp set "Love You Much"! I am going to have fun with other color combos for all the seasons and holidays!