Black and white paint, brush, stuff to paint.
Take your item (we’ll use a clay pot) and paint the entire object white. You may need two coats. Paint black spots to resemble the spots on cows. Make them irregular.
“Use outdoor/external paint for items to be kept outside.”
“Many items may need a primer first. Therefore use a white primer.”
“Items you can paint include: pots, wood furniture, rocks, pencil holders, containers of every type and much, much more.”