This is Lee Sin. He is the Blind Monk.
The guide is not quote complete. Some items may change.
Things to keep in mind about Lee Sin:
He is great solo, has a high survivability due to his movement speed. So this is something that we are going to work with.

To start. We are going to get boots. Lee Sin starts with 325 movement speed ( I believe the fastest in the game). Anybody with boots will be able to catch you though, So you want to get boots first so you can get back to your turret when you need to. This will put you at 375 movement speed. Potionsfor the obvious, you wont always be in range to heal up from minions using your shield ability

Next we are going to get a scepterTo help with staying topped up, and also to 1v1. If you aren't topped up, you will be a target to be ganked. This will also go towards building a cutlas , and then hextech gunblade.

We are again going to go back to movement speed for a while. We are going to finish Ionian Boots of Lucidityfor the CD. Since you are an energy champion, CD is nice to have. You could also go boots of swiftness, or Mercury's Treads. Staying on movement speed. You going to get a Zealwhich should be easy enough.

Now we have some decent movement speed to survive, we are going to finish Cutlassfor a little extra effect and damage. Now we are going to build a Guinsoo's Rageblade. Why you ask? Your Safeguard, and your Tempest scale with AP, and in a fight, any extra help you can get with those 2 will be huge.

Then we are going to finish phantom dancers, to help push those turrets, and also for extra healing from your lifesteal when 1v1'ing (or 1 vs 2), which I have done. Once that's finished, build a Hextech GunbladeWith the Cutlass you already have. As I said before, The AP and Lifesteal will be a big bonush with Lee Sin. And when you are waiting for energy, you can use your hextech ability for some added damage.

At this point, we have some Decent movement, and some decent attack speed and lifesteal. Which is the perfect time to build a Malady. Once that's done, Build a SheenFor some Hard Opening Hits and then finish Trinity ForceFor a little bit of all around everything that we have been working on.

Always the ability to get when available, unless your ult is available. This is the ability you will be using to harass ranged opponents. For the most part, you won't be using the 2nd part of this ability, since you will likely be 1v2. If you find you have an advantage, then go ahead and use it, but only after you have Tempest.
This is your second ability to max, after your ult. This will give you your ability to lane longer, and survive fights, or help teammates survive. The second part of this ability gives you Armor, Spell steal, and spell vamp. So make sure you take advantage of it on creeps to keep your health topped up.
This is a useful ability, but you will only get a point in it at level 4 for its slowing ability. I like to use this to resonating strike into my opponent, then quick use Tempest / Cripple to reduce the damage he does to me.
A very nice Damage Dealer. Scales AD. The this is an ability you can use either early in a fight to position your opponent where you want him, or late in a fight to finish him off. Just make sure he has cripple on him when you use it, so that if he doesnt die, you can catch up again (this is partly why we are working on movement speed as well)