Wipe the inner and outer surface of the wine barrel with a moist rag to remove accumulated grime, dust, dirt and debris. Carefully scrape off stubborn debris with the edge of a putty knife. Use a claw-hammer to remove any staples or nails that protrude from the face of the barrel.
Sand the edges of the barrel with the roughest-grit sandpaper first, then finish with fine grit sandpaper. Smooth the sides of the wine barrel with medium-grit sandpaper. Wipe off sanding residue from the barrel with a dry cloth.
Apply two to three coats of the desired stain or paint over the surface of the barrel. Allow each coat to thoroughly dry before applying the next coat.
Stand the barrel up with its base side facing upward. Measure the base of the wine barrel to determine its diameter, since the top or lid is typically damaged or broken. The base will serve as the frame for the cushion. Double-check the measurement before recording it to ensure it is accurate, since you will form the cushion accordingly.
Spread two pieces of decorative fabric on top of each other on a flat surface with their right sides inward. Trace the outline in chalk to match the diameter of the wine barrel on the fabric. Form a second chalk circle 1 to 1 1/2 inches outside the previous one.
Smooth out any fabric wrinkles or creases, and pin the pieces together, inside the circle outline Carefully draw a dotted circular outline a half-inch outside of the previous one.
Sew the fabric pieces together along the middle circle, using matching thread that complements the color of the fabric. However, leave a small gap open along the edge.
Cut along the outermost circular outline using sharp fabric scissors. Pull out any loose threads.
Insert your hand through the tiny gap you left when stitching the fabric cover. Pull the fabric out through the gap so its right side faces outward. Insert pre-cut cushion foam into the cover through the opening, Stitch the opening closed by hand.
Center and lower the cushion over the wood on the barrel's base to form a comfortable seat.