Fondant is a mixture of sugar and water made into a soft, pliable dough used to cover cakes. It can be made from scratch or bought ready-made. It is important to get a smooth finish when covering cakes to give a professional look. Fondant smoothers are plastic tools that help when covering cakes in fondant but you can achieve a smooth finish without them. Use leftover fondant dough shaped into a ball, dip your hands in cornstarch or use a piece of thick foam to smooth out the fondant on the cake.
Roll out prepared fondant 1/4-inch thick. Use cornstarch to dust the work surface while rolling the dough to prevent fondant from sticking.
Place the rolled fondant over the cake, smoothing out the top and sides with your palms. Trim excess fondant with a knife and combine the leftover fondant to form a thick ball.
Use the ball of fondant to smooth the top and sides of the cake. You can also smear your palms with cornstarch and smooth the top and sides. Alternately, try using a piece of thick foam to achieve a smooth finish.