Wear surgical gloves for this step. Make the leaves as bright or as dull as desired. Roll the gum paste out onto a smooth surface that's lightly dusted with powdered sugar. Keep the rolling pin dusted as well. Cut the leaves with cookie cutters or by cutting around a drawn pattern.
Place leaves on a nonstick surface such as wax paper to dry.
Shape the leaves by laying them over a paper towel roll, covered in wax paper, or in a cupcake liner. Leaves will dry overnight and can be placed under an oven light to speed the process. Paint veins on the leaves while still soft. Simply wet the brush and make fine lines, using a golden-yellow paste color. Leaves can be placed flat on the cake or they can be elevated by piping a small mound of icing underneath one end of the leaf.