We have developed a simple technique for modelling the structure of expanded liquid metals along the liquid vapour coexistence curve which may be characterised as a ‘correlated percolation’ method. Starting from a model for the liquid at high density, e.g. near the triple point, obtained either by molecular dynamics simulation or reverse Monte Carlo modelling, we keep the size of the model and the atomic positions fixed and remove atoms, according to criteria which depend on the coordination number distribution, until the required lower density, corresponding to a higher temperature, is reached. Small random Gaussian displacements are then added to the position of each atom to account for the increased temperature. The structure factor of the resulting model is quite close to that measured experimentally. Changes in the structure factor as the liquid expands can thus be separated into the effects of density fluctuations and temperature (or entropy).