The smaller the pivot point the lower the friction will be. In clockmaking, the pivot is likely to be a tiny pin running in a jewelled bearing. To minimise air resistance, use the thinnest string or wire for the pendulum, with a dense material for the weight (or bob as it is known). The denser the bob, the smaller it can be. If the bob is flattened and polished so that it provides a smaller surface area in the direction of swing, the air resistance will be even less. Let the pendulum swing inside a case (as in a longcase clock) so that it is undisturbed by air currents.