A manufacturing process and the semi-finished product of thermoplastic material obtained therefrom, for obtaining products with aesthetic patterns which can be perceived in semitransparency also in depth is disclosed. The process includes: (i) producing at least two initial elements of thermoplastic material with even but different aesthetic patterns, having a different concentration of the dominating coloring, at least the dominating coloring being of the bleeding type in the specific thermoplastic material; (ii) shaping the two initial elements into strips or loaves being of a submultiple width, not below ⅕ of a characteristic dimension of the desired finished product; (iii) inserting at least two of the strips or loaves having different concentration of the dominating coloring, into a workform, arranging them side by side according to a direction of side-by-side arrangement; and (iv) undergoing pressure and heat to allow the melting and hardening of the thermoplastic material into a single body.