A honeycomb sandwich sheet or panel, based on thermoplastic polypropylene, includes a structure having two flat outer films, thermowelded to a central film that includes a thermoformed blister film, with blisters repeated in a regular and continuous pattern, the flat outer films including a coextruded two-layer film, based on thermoplastic polypropylene, wherein the inner layer faces the central thermoformed film, and the central thermoformed blister film includes a coextruded three-layer film, based on thermoplastic polypropylene, wherein the two outer layers face the flat outer films, and wherein the structure includes and additional layer C thermowelded to the outer layer of the two flat outer films.