Purchase a large stretched canvas (such as 16×20 or 24×36 inches), a small tub of lightweight joint compound, and a notched plaster trowel or comb from the hardware aisle. Spread an even layer of joint compound across the canvas surface using a putty knife. Drag the notched trowel across the wet compound in arching, wave, or geometric motions to create deep 3D texture lines. Once the compound dries completely overnight, paint the entire canvas in a single coat of matte off-white, taupe, or terracotta acrylic paint.