Commercial molds for concrete garden stepping stones can be found at your local craft store. While they are not marketed for borders, simply follow the directions on the box for pouring the concrete into the mold. When the stepping stone is completely dry, position the stone in your garden, stand it upright and bury the bottom half in the soil. Continue with this process until you have completed enough stones for your border.
A silicone 8-inch-square cake pan makes an ideal mold for pouring concrete.Silicone is a quick release material, so no preparation is necessary before pouring your concrete. Impressions can be made into the surface of your concrete such as children's hand-prints, pet's paw-prints, leaves and twigs. You can also embed marbles if you want to add some color. If you choose to do this, spritz the cement regularly with water to slow the drying time so that the marbles do not fall out. Stand your concrete squares on end in a row in the garden and bury the bottom half in the soil.
Jello molds might seem like an unlikely choice for cement garden borders, but they come in fun shapes such as stars and hearts and are inexpensive to buy. Arranging a border of ornamental shapes can make an interesting accent for your garden. Be certain to spray your molds with a cooking oil spray to ensure a quick release when your concrete is dry.
Oversized cookie cutters can create interesting shapes for a garden border. Choose the shape you want to duplicate and spray it well with cooking oil. Press the cutter into a piece of plasticine clay. This will provide a sealed bottom for your cutter. Pour your concrete into the cookie cutter mold and let it thoroughly dry before removing your piece.
A simple shape for a border design may be made with a rectangular soap mold. Many of these molds are designed with beautiful raised images in the center. They can be placed end to end to make a very impressive garden border. These molds must also be sprayed with cooking oil for an easy release of the poured concrete.