Fondant is a sugar gum paste that can be rolled, cut, sculpted, or moulded to offer a wide variety of options for decorating cakes and other baked goods. While it looks fancy, you can purchase rolled white fondant at any cake speciality store, some craft stores, and online. Sea shells have a simple shape and can be recreated using the fondant like clay. The technique allows you to customise the sea shells to be the size and exact shape that you wish.
Open one package of white rolled fondant and set it on a counter that has been sprinkled with cornflour to prevent sticking.
Flatten the fondant to a sheet that is about 3 mm (1/8 inch) thick using a rolling pin that has been rubbed with cornflour.
Cut out a wedge shape from the fondant using a sharp knife. If you'd like the edges of the sea shell to have ripples, you can cut the curved edge in a wavy line.
Tuck the point of the wedge beneath the shell to give it a more realistic shape. Set the sea shell on a platter covered with waxed paper.
Gently scrape the very tip of your knife to create lines that run vertically through the shell to give it more detail. The knife should only barely be grazing the surface to make the indentation rather than cutting all the way through.
Repeat with the remaining rolled fondant until you have as many sea shells as you desire. You can create many different sizes and textures to give the sea shells variety.
Add a little colour to your sea shells by brushing them with powdered or liquid food colouring, using a soft paint brush.