Check out this great design from cafepress Flower Mug
Flower Mug. this pretty flower was growing in front of the house I stayed at in South Africa. Product Information Small measures 3.75" tall, 3" diameter; Mega measures 4.5" tall, 3.75" diameter Small holds 11 oz.; Mega holds 20 oz. Black color-changing mugs available in small only and are heat sensitive. The color-changing mug starts out all black in color. Simply add any hot liquid to the mug and watch as the mug changes from black to white and your unique design is revealed! Dishwasher and microwave safe