Panel and method of producing a panel

A belt roller system for applying a surface structure in a floor panel or wall panel, said system comprising:

• at least one upper endless belt and at least one lower endless belt, wherein each belt is rotatable around at least two pulleys,
• at least one drive unit for rotating the upper endless belt and/or the lower endless belt,
• wherein at least part of the upper endless belt comprises a surface structure and/or wherein at least part of the lower endless belt comprises a surface structure,
• wherein the upper endless belt and the lower endless belt are positioned substantially parallel to each other such that a panel can be transported between the upper endless belt and the lower endless belt such that the surface structure of the upper endless belt and/or the surface structure of the lower endless belt is transferred into the panel upon transport of the panel between said upper endless belt and said lower endless belt, and
• at least one cooling unit configured for cooling at least part of a surface of the panel via the upper endless belt and/or lower endless belt, while the panel is between said upper endless belt and said lower endless belt,
• wherein the surface structure of the upper endless belt and/or the lower endless belt comprises a plurality of protrusions and recessions, wherein a height difference between at least part of the protrusions and recessions is at least 1 mm, and
• wherein a length over which the upper endless belt and the lower endless belt are positioned substantially parallel to each other is at least 30 cm or at least 50 cm.