A measured amount of a material that is crosslinkable by impingement of a suitable form of energy, especially UV light, is introduced into a two-part mould of which the cavity determines the shape of a moulding to be produced. The two mould halves are held a small distance from one another so that a thin annular gap is formed between them, which gap is in communication with the mould cavity and through which gap excess material can escape. The crosslinking is triggered by impingement of the selected form of energy, the impingement being spatially restricted to the cavity by suitable masking so that material disposed outside the mould cavity is not crosslinked. In that manner mouldings are obtained that do not require subsequent mechanical processing, and the mould is reusable. The process is especially, but not, however, exclusively, suitable for the manufacture of contact lenses.