We are all familiar with the use of cement and concrete as construction materials. Lesser known is its use for interior furnishings; these can range from sculptures to more everyday concrete objects.
Both cement paste (no sand or aggregate) and concrete can take a good polish and this makes them ideal for a range of surfaces. Remember, the well-known Terazzo tiles are produced from concrete with a ground and polished surface. Concrete worktops are also becoming increasingly popular.
One key characteristic of cement and concrete is that they can create an infinite variety of shapes, thanks to the use of moulds. Once hard they can be removed from the mould and polished up or even stained. Moulds can be made of metal, wood, plastic or even plaster. The key is to prevent the concrete sticking to the mould (this is similar to baking) by using some form of mould release agent (e.g. a specific type of oil). I’ve never tried cling film or Teflon sheets, but they might work as well.
Perhaps an easy starting place would be a concrete plant trough for the garden, where the surface finish is not as critical as it would be for something kept inside the house. For a smother finer finish leave out the coarse aggregate and just use cement and sand, but more cement than in a brickwork mortar. Using white cement (available in bags from many builders merchants) can give a different look and various concrete pigments are also available to add colour. Pigments work best with white cement if you want good clear colours.
Simple objects like storage containers or pen holders may also be worth looking at.
You are only limited by your own imagination, so try an experiment or two!