Cut a piece of plywood or a pine panel into a square or rectangle that is the desired size of your artwork. Paint the board in a color that complements the color scheme of your mosaic, and let the paint dry.
Lay out the paint-chip samples in the order and spacing you want them to appear in your mosaic.
Apply a straight line of adhesive spray across the top of the board where you will place your first row of paint-chip samples. Lay out the samples in the order you have chosen.
Spray a second line of adhesive and lay out your next section of samples. Continue spraying adhesive and applying paint-chip samples until the entire board is filled, creating your mosaic.
Spray the entire board with adhesive once all the samples have been laid in order to ensure that none come loose. Reapply paint to the edges of the board to avoid any sticky spots caused by the adhesive spray. Let the adhesive and paint dry completely.
Apply three coats of decoupage glue over the mosaic to create a smooth surface. Allow the board to dry overnight.
Apply stain to the entire piece, using a rag. Pay special attention to the spots in between the samples and to any cracks. This will make those spots look darker and more distinct. Let the stain dry before hanging or displaying your finished project.