Apply a thin base coat of beige to the surface being finished to neutralize the original light tones. Use a darker brown to cover dark-colored surfaces.
Make long diagonal strokes of the leaf green paint over the basecoat with a paintbrush. Leave about 15 percent of the beige coat showing in random gaps across the surface.
Dab the light green paint, using a sponge, onto the gaps in the dried dark layer. Only cover half of the visible gaps of the basecoat. Cover the other half with the yellow-green paint.
Apply a thin layer of yellow-green paint over the light green paint and light green over yellow patches. Use the sponges to blend the separate colors for a natural look.
Dab the copper paint onto the dried layers of green in a light, random pattern. Aim the paint for the darker areas first.
Let the copper dry completely. Inspect the finish. Use the various colors to increase or decrease the copper color to your liking.
Brush clearcoat onto the dried copper and green paint. The clearcoat should cover the entire surface evenly.