What i mean, what build you CANT do to thresh.Even if he has ap ratio at all spells, you can make any build to him.Pure AP, Tanky, Support, even AD and i heard he is good at jungling but has slow clear.I even tried something Hybrid (ap + ad).He is like an universal champion, he does verry well on every lane/ jungle.
So what can be impossible to build on him?

*possible*

CDR Tank. He has strong CC, but long CDs, little AoE, no nukes other than ult which makes him stand in the middle of the fight... so CDR Tank it is.