A pendulum is about as simple an object as this list contains, a weight, commonly a faceted crystal point, a brass bob or a turned wood ball, hung from a chain or a length of thread, and the simplest working version is nothing more than a ring or a key on a string, requiring no purchase or craftsmanship at all.
Who makes them, and who uses them
Crystal and metal pendulums sold for dowsing and divination come from ordinary jewelry and lapidary workshops rather than any specialist ritual maker, and there is no restriction on who may own or use one. Many practitioners nonetheless treat a new pendulum as needing to be cleansed or attuned before its first real use, commonly left in moonlight, passed through incense smoke or simply held and used slowly at first, a practice framed as calibrating the object to its user rather than as a formal consecration.
Personal ownership and replacement
Because a pendulum is considered by many users to become personally attuned over time, a lost or broken one is generally replaced rather than mourned, but some practitioners are reluctant to buy a used pendulum secondhand without cleansing it first, treating it as carrying something of its previous owner's use in a way a brand new one does not.