Why not carve a cat in polystyrene. A cat sitting down made of expanded polystyrene.

Draw your design and cut the profile shape in card, pin the card to the polystyrene, cut the shape out with a hot wand tool, shape the material with a wire brush and smooth it into a final shape with sandpapers of various grades.

One the model is made it is ready for painting or you may wish to hard coat it with something first.