Lightly dust silicone mold cavities with cornstarch. Fill cavity with fondant or gum paste. Press down on fondant or gum paste with fingers to push into all areas of the cavity. To evenly distribute the material, you can also press with Shaping Foam.
Trim excess fondant or gum paste using spatula or palette knife.
Turn mold over and flex to release shapes. Follow project instructions for placing design on your cake or let dry as needed.