Preformed liners

The only virtue of pre-formed garden ponds is that they are easy to install: you bring it home from the garden store, dig out some soil and plonk in the preformed pond. It then looks like a preformed pond which was brought home in the car and plonked down ie UGLY. The typical construction materials for preformed ponds (PVC and GRP - Glass Reinforced Plastic) are suited to sleek shapes, like boats, but are totally unsuited to the shapes used for preformed garden ponds.