How to Make a Wall Look Like a Stone Castle Wall With Plaster

Sand the entire wall's surface using fine-grain sandpaper, which will remove any rough or uneven areas from the wall.

Vacuum the wall and surrounding areas using a shop vacuum, then wipe off any residue from the sanding using a damp washcloth. Allow the wall to air dry for 30 minutes.

Spread a one-half-inch-thick layer of wall plaster evenly onto a rectangular trowel. Press the rectangular trowel onto the wall, then gently slide the trowel off to leave the patch of plaster attached to the wall.

Spread a one-half-inch-thick layer of wall plaster evenly onto a triangular trowel. Press the triangular trowel onto the wall next to the first plaster patch, then gently slide the trowel off to leave a triangular patch of plaster attached to the wall.

Repeat until you've covered the entire wall with alternating rectangular and triangular plaster patches. Space each plaster patch out by one-half inch. Leave a section unplastered measuring 12 inches wide and 18 inches high.

Moisten a round sponge, and tap the wet sponge over the surface of each plaster patch. This will make the plaster patches look like stone. Allow the plaster to air dry for 12 hours.

Pour dark gray texturized paint into a paint tray, then coat a 2-inch flat paintbrush with the paint. Apply the paint to the plaster stones and in between each stone. Allow this first layer to air dry for 8 hours.

Pour medium gray texturized paint into another paint tray, then coat a 3-inch round paintbrush with the paint. Tap the tip of the paintbrush over the surface of the stones, but not in the spaces between the stones. Allow the paint to dry for 8 hours.

Pour light gray texturized paint into a third paint tray, then coat the 3-inch paintbrush with the paint. Tap the paint off the brush so that only a small amount remains on the brush, then lightly tap the paint onto the stones, but not in between the stones. Allow the paint to dry for 8 hours.

Paint the section that is unplastered using colorful latex paint and a one-half-inch round paintbrush to resemble an outdoor scene. This will make the unplastered area look as though you are looking out of a castle window. Allow the paint to dry for 8 hours to complete the castle wall.