Pills are generally made from powdered medicines, so the preparations for making powder are followed to begin with. Then the powders are formed into a 'pill mass' with a suitable liquid.
In the Western Tradition, Pills were most commonly used as the administration method for purgative medicines. Administering purgatives in pill form has several advantages: the dose can be strictly regulated; foul-tasting or irritant medicines reach the stomach without affecting the mouth or throat, or offending with their taste; it was also long believed that the slow dissolving of a pill allowed the purgative medicine to reach deeper and purge more effectively. It also means that strong or harsh purgative or cathartic medicines are not 'dumped' into the system immediately, but rather, dispersed over a period of time to avoid any harsh reaction on the stomach or intestines.
Traditionally in the Western Tradition, this semi-solid pill mass would be kept in a container, usually being covered with an oiled piece of leather. Then, when they were to be prescribed, a piece was taken and pills of a suitable size were rolled as required.
Pills can be made of powders by adding a variety of different liquids: Honey, Oxymel, Syrup, Mucilage, clarified Juice, Rice water, etc. The size of a pill was often given in reference to a seed, for example a Hemp seed, Pea, Chickpea etc.
Pills may be coated once finished. Rolling pills in a tray with a little hot wax can give a wax coating which can keep the pill almost indefinitely. In other cases, the pills may be rolled in sugar, a gum, a mineral such as Pearl or Cinnabar, or in the case of special and 'noble' pills, Gold or Silver leaf.