Moulding video discs

An arrangement for impressing a surface of a thermoplastics foil with a relief structure, the arrangement comprising a pair of substantially parallel mould blocks, means for applying pressure to said mould blocks, a pair of substantially parallel stamper plates mounted between the mould blocks, at least one stamper plate bearing a negative impression of said relief structure, and interposed between an adjacent mould block and stamper plate a resilient material compensator, as hereinbefore defined, wherein at least one compensator has a convex surface, the ratio of the diameter of said surface to the depth thereof being no less that 340 and no greater than 3400, which arrangement is capable of impressing a thermoplastics foil positioned between the stamper plates.