Six-pack abdomen illusion tanning pattern

Six-pack abdomen illusion: it would look good to tan the skin on the abdomen unevenly, in a certain pattern, shading it in a way that resembles/imitates, or just enhances a more or less existing six-pack. The selective shading/colouring could be achieved by sunbathing (once or repeatedly) with a film foil on the abdomen. The mass manufactured foil is sprayed more / less densely in an appropriate pattern, acting as if more / less sunscreen was applied, achieving less / more tanning. Foil in different sizes (S/M/L). In the case of repeated sunbathing with the foil the foil needs to be placed in the same position/location: the belly button could be the anchor point. The user would draw a circle on his own foil with a pen when using the foil for the first time, then later would just place the foil so that the circle is on his belly button again. A drawer/painter applies shading to make the viewer see/construe a curved surface - uneven tanning would work like that. There are six-pack, armor, Superman shirts; they look OK no matter where the Sun or main light source actually is, so hopefully it would never look odd or be explicitly counterproductive that this skin shading exists, cancelling out or interfering with the real shades if someone’s abdomen is not flat/plane but has more or less real six-pack. Besides this foil that uses tanning and needs to be repeated when the tanning fades, henna painting or tattooing might also work. The foil would be cheap to manufacture, so unless it can be patented, its price cannot be high, as it is easy to enter this market, many manufacturers would drive down the price.