Hello, and thank you for giving my guide a read, and with this being my first one, bear with me. Blitzcrank is pretty easy and fun to play, but requires some work to master. Typically, I despise tanking, so this is my basic AD off-tank build for him. Different situations require different builds, but this seems to cover everything I want out of him, and is what I generally build against any normal, balanced team.

Honestly, runes don't make a huge difference on this guy, and you could get away with many different rune builds, but these are just the ones I have, and seem to be the ones that maximize damage early game (ArPen), while still helping throughout the game (cdr). Mana/5/lvl helps but this one can definitely be replaced, seeing the build focuses on rushing a manamune, and other mana items. Again, just the runes that I had available, maybe straight mana/5 would be better for him and his early game mana problems (which I don't have with the per level seals...).

My mastery selection may seem a bit odd, but I stand firm to it. People will want to hate for not getting a point on the end of a tree, but I find that everything I need for him is all mid-tree. Feel free to change it up according to your own style, it probably won't affect much.

My items focus on mana and damage, taking advantage of his mana barrier, and the obscene damage his power fist can pump out. I also focus heavily into movement speed, seeing that his overdrive, ghost, and ms5 boots can basically catch up to anything (then grab, punch, and kill).

Well... ghost and exhaust fit into my mastery build, and have come in handy plenty. Again, I take these to dominate movement speed.

To sum it up, using this build you should have good survivability, good damage, and good control. You'll have lifesteal for getting hp back, ~3k hp, a hefty mana barrier, some mr and armor, and lots of cc and movespeed to get away if all else fails. GL HF :)