Whitesmith Wizard
The arcane mysteries of magic are not restricted to the warlike and adventurous. Guildsmen have their own peculiar ideas on how magic is best used, and none more peculiar, perhaps, than the tradition of the Whitesmith Wizard. Working from the same principles as the mundane craft they have mastered, Whitesmith Wizards specialize in the magical manipulation of metal in the finest and most delicate manner. With acid-etched tinplates serving as a spellbook, these eccentrics bend the very structure of their materials to suit their visions of art and beauty.
Reverse Transmutation
The mysteries of metalworking sometimes require materials be more practical than valuable. At level 2, a Whitesmith Wizard can turn gold, the noblest of all metals, into any lesser metal (ie not platinum). It takes one hour for each pound of gold changed in such a manner. The volume of metal is unchanged even if the weight significantly changes. At level 10, the Whitesmith Wizard can also turn lesser metals into any other lesser metal at triple the speed of gold reverse transmutation.
Equal Exchange
All trade is nothing but an extension of natural principles. Starting at level 2, a Whitesmith Wizard may choose to consume an etched metal sheet from their spellbook when casting a spell. In doing so, they add their proficiency bonus to attack or damage (DM's discretion), but cannot cast the spell again, nor remember the details of its rituals, until the spell is once again retranscribed into the Whitesmith Wizard's spellbook.
Alwyte Armor
A artisan who will not trust their own handwork is no artisan at all. Starting at 3rd level, a Whitesmith Wizard may choose to etch into their own armor personal motifs or details of their deeds. After doing so, they enjoy a +1 proficiency bonus on all metal-related skill checks (even if the relation to metal is tangential) for as long as they are wearing the armor. This bonus does not extend to those other than the original etcher who wear the armor, including other Whitesmith Wizards. At 10th level, the Whitesmith Wizard also enjoys an additional +1 AC when wearing the armor.
Charged Metal
To a Whitesmith Wizard, metalwork is as natural and comfortable as a hand or a finger. At level 6, a Whitesmith Wizard can channel their spells through any uninterrupted metal object they can touch. The point of departure along the object for the spell is determined by the wizard but must be within the Wizard's line of sight. The object can be made of multiple metals, such as an iron sword with a gold hilt, but cannot have its path from the Wizard's touch obstructed by ANY nonmetallic material.
Metalbender
As water is the lifeblood of man, so too is metal the lifeblood of artisanship. At 10th level, a Whitesmith Wizard can treat molten metal as water for the purposes of spellcasting that affects water or liquid. This does not allow the Whitesmith Wizard to turn solid metal into molten metal.
Lore Of Metal
At 14th level, a Whitesmith Wizard has become a legend of their craft. A Whitesmith Wizard can expend a spell in a a spell slot one level higher to treat solid metal as water or a liquid for the purposes of the spell's effects. This does not superheat the metal. The spell can be cast at two levels higher to superheat the metal.
Developers notes
This subclass was developed out of a randomly rolled character who was a whitesmith (a worker of tin, silver, and/or gold). I decided I wanted him to be a wizard, but didn't like any of the subclasses/schools (or artificer), so I decided he followed an obscure magical tradition of his guild based around metalworking. It's not meant to be particularly powerful or balanced. Just some fun fluff for you metalworkers out there.