Although the chandler’s craft required some specialized skills, Medieval candle making wasn’t so difficult as those contemporary professions requiring apprenticeships and journeyman experience. As a result, chandlers historically weren’t among the wealthiest craftsmen.
The chandler’s raw materials were few and easy to obtain: flax or wool for candle wicks, beeswax or tallow for the body of the candle, a dipping pot large enough to accommodate the intended size of the candle and a heat source to melt the wax or tallow.
Chandlers that kept bees harvested both beeswax and honey, usually by building a small fire of green wood beneath the hive, the smoke from which would temporarily drive the bees away. The honeycomb would typically be filtered through a porous cloth, with the honey first obtained used for sweetening and the “last” honey – that obtained bt wringing out the cloth at the end of the process – going toward the production of mead. The beeswax went to produce candles.
Chandlers that rendered tallow would obtain it from boiling animal fat in water with a bit of dissolved salt; the tallow would float to the surface and be collected. Note that beef or sheep fat was preferred for this process, as candles made from pork fat burned smokily and smelled terrible.
There were essentially two methods for making candles: repeatedly dipping the wicks into a deep pot of wax or tallow, or melting the wax and repeatedly pouring it down the suspended wick. In either case, the candles typically had to be molded into their final shape by hand, and the bottoms of the candles needed to be cut so that they were level at the end of the process.
In a D&D fantasy setting, chandlers may be a bit more well-to-do, particularly if their craft entails including making candles of different colors, scents, or even making candles compatible with certain magic rituals.