By applying gel over a stencil and then flash curing the product before it had a chance to level...
Nail Art Tutorial: 3-D Orange Party Nails
Step 7: Finish the first layer of your flower by placing another 2 balls alongside your first petal in a circular motion and follow steps 3-6 working with one ball at a time.
Step 8: For the second layer of petals you will need another 3 balls. This time, make them slightly smaller so they will create smaller petals. With your first ball, place it a few millimeters closer to the center of the flower and slightly overlap it over the 2 adjacent petals. Follow steps 3-6, but this time do not press as hard downwards as you will press the petals too far into the underlying ones. It helps to keep your sculpting brush slightly vertical. Work with one ball at a time.