Tannan, as the foremost arcane mech designer in history, has created a bunch of weird spells specifically to help with that very problem. Consider how useful it would be to have a medium-level divination that functioned like True Strike, only for reaching your Craft DC.
Very useful, indeed.
And I assume he could have gotten some outside advice and probably dug up one of the last surviving copies of Thee Boke of Golymcrafte
all the back issues of Enchanter's Quarterly
and traded three magic wands, a uncut diamond the size of an apple, and a necklace made from a revenant's teeth for the original edition of The Tome of Livynge Magicke
and probably did some serious praying to the elven deities and had a magic item made that gave him a bonus to Mechcraft (Cost: Bonus squared x 100)...
All of which stacked together would give him just about enough to make a City-Mech F out of living material.
The question is, of course he'll use his newfound expertise for the benefit of elvenkind, but one of the new questions is:
Will the Gearwrights ever find out those spells are in existence? I can't quite decide if they'd be interested, ecstatic, or horrified.
The other new question, which arrived upon running over Tannanliel's characteristics in my mind, is:
What's its personality?
The big steam-driven city-mechs have their own minds, as the cogworms have discovered. And they're just moving pieces of metal and stone put together.
Tannanliel is made of living wood and it's powered by magic. Magic has always had an inclination towards forming its own mind.
The idea of Tannanliel gaining sapience is quite...interesting.[/i]