How to Make Concrete Edging Molds for a Garden

Create a diagram of your mold design. The best designs are simple, linear patterns. For example, design a box for a concrete edger that measures 20 inches long by 4 inches wide. The box will feature a bottom panel base, two side panels, two blocking side panels and two end panels. The bottom panel base must be 4 1/2 inches wider than the final measurement of the concrete edger, to allow for the attachment of the wood blocking and melamine side panels to the bottom panel. For example, for a mold that measures 20 inches by 4 inches, design the box's bottom panel to measure at least 20 1/2 inches by 8 1/2 inches.

Cut the melamine wood according to your measurements. Set aside.

Cut two sections of 2-by-4-inch lumber according to the length measurement of your bottom panel. This wood will serve as the two blocking side panels to support the melamine side panels on each side of the box. This blocking is important, as it prevents the melamine from bulging out from the weight of the concrete and provides a surface upon which to screw the end panels. Screw the 2-by-4-inch blocking sections upright with the 2-inch side placed onto the face of the bottom panel and flush along the long sides of the bottom panel. The mold will, so far, look like a "U," consisting of two 2-by-4-inch blocking sections flanking each side of the bottom panel board.

Place the first melamine side panel next to the 2-by-4-inch blocking board on the inside of the box. Screw the two boards together. Repeat the procedure with the second melamine board. The mold so far consists of a bottom panel with two side panels -- the blocking panels and the melamine panels -- on each end. The melamine wood serves as an inner side panel on each side and the 2-by-4-inch wood provides a stiff, supportive, outer side panel on each side.

Screw the end panels to the ends of the 2-by-4-inch blocking side panels.

Apply a thin bead of silicone caulk along all joints inside the box where two sections of wood meet. Wearing a rubber glove, smooth the bead with your finger along the joints to fill the joints and smooth the surface. Allow the caulk to dry thoroughly before pouring concrete into the mold.