The container has moulded moisture-permeable walls (10) made from a granular material such as gravel, the particles of which are coated with a resin which is preferably transparent after polymerisation. The resin sticks the particles together by their contacting points, leaving gaps between for moisture to pass through. After moulding, using an outer mould and an inner core with the resin-coated gravel between, the container is left with a shiny surface and walls that are permeable to water. The inner surface of the container can be sealed with a layer (9) of resin- impregnated glass wool.
