Cut two pieces of wood 4 inches long and 1 inch wide, using a saw. In the center of one of the cut wood pieces. cut out a circle. With wood glue, screws and a screwdriver, form an L shape by connecting both pieces. Make sure that the circle is big enough for the floral vase to fit into. Sand any rough edges with sandpaper.
Paint or stain the wood and paint the floral vase in any color you choose, using a paintbrush and allowing 30 minutes to completely dry. Sometimes wood will soak up paint, so more than one coat may be needed. Once dry, fill the floral vase with foam if you are using artificial flowers.
Arrange the flowers by pushing the stems of the artificial flowers into the foam. If you're using real flowers, trim the flowers to the desired length with scissors and add water and the flowers to the vase.
Place a screw into the wall where you wish to place the sconce, using a screwdriver. Create a notch into the back of the sconce big enough to fit over the screw hanging in the wall, so that the sconce can be hung. Attach to the back of the sconce. Place it on the backside of the wood without the circle cut in the middle.
Place the vase inside the circle you've cut. Decorate to your desired taste with more flowers and moss as needed around the sconce.