I worked on a plywood base so I could move the wall during its construction. The wall I made measured 30 by 35-inches and weighed about 50 pounds. You can use the same techniques to make a smaller version. Make a base: Place metal rulers on a parchment paper lined surface so they form an open space that measures about 30 by 35 inches. If you don't have metal rulers, you could also use modeling clay or wood rulers. Pour tempered dark chocolate inside the open space to form a 1/2-inch-thick layer. Dark chocolate is stronger than white chocolate so that is the reason it is used at the base. When the chocolate has set, remove the rulers and peel off the parchment paper. Repeat this process with a layer of white chocolate. Use tempered chocolate to adhere the white layer to the bittersweet layer. The white chocolate layer will be the grout between the bricks.
Make the bricks: Mix red coloring to a large bowl of tempered white chocolate. Use an offset spatula to spread the red chocolate over the part of the base that will represent the brick layer. This layer should be about 1/2-inch thick. Use the back of the offset spatula to roughen the surface of the bricks to make them more realistic. Make sure you leave space for the door that will be added later. Use a straight edge as a guide as you draw your finger through the red chocolate to create the grout lines. My centerpiece had 13 rows of bricks. The bricks are about 4 inches wide by 2 inches tall with a 1/2-inch grout. Allow the chocolate to set. When the chocolate has set, use an airbrush with red and black paints to give the brick character. Make the door: Use an offset spatula to spread a 1/4-inch-thick layer of tempered bittersweet chocolate over a sheet of acetate. Let the chocolate set slightly. Use a paring knife to cut the outline of the door. You should size this to fit the opening at the bricks. My door was 11 inches wide by 23 inches tall and had a curved at top. When the chocolate is set, peel off the acetate. At this time, you can also cut the door handle and 2 hinges. My hinges were each 1-inch by 2.5 inches and my handle was 11/2-inches in diameter Use your airbrush to paint graffiti on the wall.
Sources: Chocolate Melter: Demarle Chocolate Cold Spray: PCB in France 011 33 0388 587333