How would one go about making a Metal Bender à la Avatar?

[John and KARSG!!!]

I'm aware that the Kineticist exists but as far as I'm aware they have no way of manipulating metal, so how would I do it?

[DeathlessOne]

Can you clarify what you mean by 'manipulating' metal? Because kineticists with a double focus in Earth get access to Metal blast and other useful metal abilities. If you mean manipulating existing metal, you would be more inclined to look at the Aether element that focuses on telekinesis.

Metal kineticist stuff:

Metal Blast, Magnetic Infusion, Magnetism, Impale, Clockwork Puppet, etc, etc

[Ryze Kuja]

Detect Metals and Ores and Transmute Earth to Metal (3pp) would be a good start. Permanent Animate Object spells on metal whips that you can extend and retract would be the next step.

[avr]

This sounds like a job for Spheres of Power. It does tightly themed spellcasters and similar better than Paizo's material.

[Sysryke]

Not sure how to get the martial arts aspect into a wizard, unless you want to multiclass, but there is a metal school of magic for wizards that should take you in the right direction. 3pp spells will probably also be your friend.

[Erik Lehnsherr]

I played this character as a Metal Kineticist until 13-14ish in PFS with Improved Unarmed Strike to pick up Deflect Arrows. So, most of the way to Metal Bending anyway.

Kinetic Cover gave the feel of manipulating large amounts of material to form shields until Shift Earth(and greater) came online, though that was mostly for Construction purposes.

Impale was pretty effective from what I remember, though expensive to also make a metal blast.