An injection-moulded piece that has a plastic base layer, a transparent or translucent cover layer, and a layer containing individual decorative elements located between the base and cover layers. The decorative elements are at least partly embedded both in the cover layer and in the base layer. The method for producing the injection-moulded piece, wherein decorative elements are placed on a sticky cover layer and a base layer is applied to the decorative elements by injection moulding. The individual decorative elements are applied to the sticky surface of the cover layer, by a random process, and if required, a second cover layer is applied, the decorative elements are at least partly embedded in the cover layer, waiting for the cover layer to dry, and a base layer is applied to the decorative elements by injection moulding so that the base layer embeds the remaining part of the decorative elements.

A method of shortening cycle time required to compression mold shingle or tile is provided, wherein carrier plates are comprised of a surface material and a base, and receive a thermoplastic material, thereon. The roofing material is applied to the carrier plate and the carrier plate is subjected to induction heating, by which its surface material has its temperature raised, without substantially raising the temperature of the carrier plate base, such that the thermoplastic material applied thereto is kept heated in the compression mold. Cooling of the thermoplastic material is by heat transfer from the carrier plate surface material to the carrier plate base, and with both materials having good heat conduction capability. The carrier plate surface material has a high receptivity to being heated by induction heating relative the carrier plate base. The carrier plates are serially delivered through the process, to the compression mold.