Arcane Guild of Artificers

Artificers produrce and enchant magical items explicitly those with a magical application. They make tools, design and adjust foci for specific needs and much more.

For example, an armour-smith might craft a magical armour that protects against magical fire. He could produce that with his normal tools and with certain rituals. But, if he were to aim for the best possible product, he would very likely order special tools like hammers and other tools from a Master-Artificer or at least a Journeyman. It would be quite as likely that he might oder special metals from an Alchemists.
All this would make the armour much more reliable, much more effective but of cours at a price, in gold and in time.

Many of the articifiers are master craftsmen in some field by themself and well done objects make them excellent money. Sure, almost all other magic users have at least a basic unterstanding od enchanting but, just as with potioners, there is a difference, a step up in ability, undertanding and the resulting products.