Here we have an idea to try and use the primary colours and the neutral colours with tempera paint.
First we draw the fence (high 11 cm, wide 24 cm, divided in 12 planks, each one 2 cm wide) with a pencil. Then we draw three or more cats, with simple lines and stylised shapes.
After that we retrace the lines with a black permanent marker. We can use the 12 planks as if they were the 12 wedges of the colour wheel: we start painting the primary colours, and then we mix them two by two creating secondary colours. The tertiary colours are created mixing a primary with a secondary color. The cats are painted with neutral colour. The task is to create a scale of 5 or 6 different greys just mixing black and white. The background is painted with a solid colour.
At the end we retrace the lines with a black permanent marker, covering possible flaws on the edges, and we draw the wood grain of the planks with a pencil.