This guide on top lane / jungle Blitzcrank is based on how I enjoy playing Blitzcrank.
In the current meta game, Blitz is quite under powered although due to the current buffs he has become more viable in different aspects of building him. The reason why i find him underpowered in the current meta is because of his lack of sustain for such an upfront bruiser without any real escape mechanisms.

Blitzcrank has good traits of an AP Caster, Attack Damage Melee Carry and an Upfront Bruiser but does not excell at any of these roles. His kit is quite strange as his ratios on his Q and Ultimate inspire you to build Ablilty Power but his W and E encourages you to build attack damage and his Passive encourages to build mana.

Whilst Blitzcrank's kit is quite derranged, his initiating ability or his ability to disposition an enemy on the opposing team is the best. If you arent great at using skillshots then Blitzcrank isnt the champion for you as his signature Q requires some skill.

Pros-
-Very Rewarding Champion when Mastered
-High CC
-High Movement Speed
-Shines Mid-Late Game
-Very Fun
-Very Strong Ganks
-Strong in Early Game invasions

Cons-
-Struggles During Laning Phase
-Hard to Farm with
-Loses most Trade offs Early Game 1v1
-Squishier side of Tanky Champions Early Game
-Slow Jungle Clearing
-Zero Sustain

In Top Lane I run the current runes above.
The 15 attack damage from Marks and Quints is to help my ability to last hit in lane as Blitzcranks Attack Animation makes it quite difficult to last hit perfectly, This changes a normal 59 Atack Damage at lvl 1 to 74 Attack Damage which benefits Blitzcranks very weak early game.

I run health/lvl seals as I want to benefit from my Late Game as much as possible, Allowing me to buy more armor/magic resist/damage related items rather than health. You may also want to run Flat Armor Seals as they are really beneficial vs Attack Damage Bruisers, but it really comes down to preference.

For Glyphs I run Magic Resist/lvl, this will benefit Blitzcranks Mid-Late game where i want to gank and teamfight as much as possible. For Blitzcrank its inevitable that you will take a lot of magic damage so to counter that i run these Magic Resist runes, for an alternative to the MR/LVL runes you can also run Flat MR, I wouldnt run CDR runes because i find late game with the help of the Blue Mushroom I have the full 40% CDR.

Runes for when Jungling-

When Jungling with Blitzcrank i run completely different runes besides my Glyphs.

For Marks and Quints I run Armor Penetration.
This will benefit my Damage Mid Late Game to Champions and it will also benefit my damage from Blitzcranks E ability.

For Seals I run Flat Armor which is a must for jungling with Blitzcrank. This will reduce the damage you take from all jungle camps which allows Blitzcrank to gank more often.

Glyphs are the same for Top Laning.

Masteries are Pretty Self Explanatory.

I put one point into the offensive tree to benefit from ignites + 5 ability power and +5 attack damage, this isnt needed for jungling. The defensive tree helps my Mid-Late game reducing the damage taken and making Blitzcrank more beefy.

I do not put any points into movement speed as Blitzcrank is quite fast after building Mercury Treads and Trinity Force reaching around 406 movement Speed. This + his w makes him very mobile therefore I put points into other parts of the utility and defence tree where I know Blitzcrank can benefit from more.

Flash is pretty much standard on all champions.
This allows you to make plays and it is pretty much Blitzcrank's only reliable escape.

Ignite is to make your kill pressure in Top Lane Very Stronk.
Also because Blitzcranks early game is quite weak, I run Ignite to add pressure to the enemy when they are thinking of diving, if you can outplay the enemy under your tower you may be rewarded with a kill due to ignite. It also gives you the ability to secure kills when diving, Since Blitz Lacks hard executing power.

You dont really need exhaust with Blitzcrank unless you know that they can rollover you under your own tower.

Teleport can be a good choice of a summoner if you think that you and your enemy Top Laner will just farm all day, and that his choice of champion is not too over aggressive.

Smite is essential for Jungling. Jungling without smite shows traits of a bad player who doesnt understand what pressure smite brings to dragon and baron security. It also helps you secure buffs and steal buffs and significantly reduces you Jungle Clear time allowing you to at least not fall too far behind in levels when it comes to Mid Game.

Ghost is the only other summoner i would run on Blitzcrank Top Lane, The Mobility is nice and it allows you to reach the enemy carries faster, and be too fast for anyone to chase you.

Starting Items:
Either Armor + 5 HP Potions
or
Boots and 3 or 4 HP Potions

Core Items:
Trinity Force- The amazing overpriced item that syncs perfectly with Blitzcranks Strange kit.
Banshee's Veil- Gives Health, Mana, Sustain in Lane through Catalyst, Magic Resist + Spell Shield. Whats not to love?

Boot choices:

Ninja Tabi- for Low CC/Heavy AD Team Comps
Mercury Treads- for CC/AP lanes/I can decide so ill just grab this anyway
Ionian Boots of Lucidity- Low CC/Im Stomping so ill take the extra CDR
Boots of Mobility- Low CC/I like to be fast and gank a lot.

Damage Items:

Atma's Impaler- Gives great Damage + Armor + Crit Chance, whats not to love about it? Also with 3000 health you would get 60 Attack Damage
Infinity Edge- A nice item on Blitzcrank as it makes your Late Game damage very high. The crit damage also stacks with Blitzcranks E. Works well with items such as Atma's Impaler and Trinity Force.
Wriggles Lantern- Explained Below.
ManaMune- Many players enjoy using this item on Blitzcrank, It gives great damage, more than Atma's Impaler would in fact Late Game when it is fully stacked. I prefer to avoid this Item in general as there are always better item choices, Atma's Impaler gives the added bonus of Armor and Crit Chance which scales better Late Game than ManaMune, ofcourse you could experiment with both items becoming an Attack Damage Carry but for competitive play it is a bad option since any good carry on the enemy team can kill you in seconds regardless of your passive. ManaMune is also very hard to stack up and makes you waste CoolDowns just to stack the Mana, which is unbeneficial in general during. It is an item of preferance, and I would not tell anyone not to use it.
Last Whisper- This item will make your late game damage massive, increasing the damage on your auto attacks and also benefit your triforce and e skill. This is what you would build if the enemy team is stacking armor and your jungler is very tanky, this is not to be bought when you are jungling yourself as you will be running ArmorPen marks/quints. I would usually consider this item when I beleive i need to be a major source of damage for my team therefore risking the survivability of not having Frozen Heart and Banshee's Veil and instead transitioning into an attack damage champion with wriggles and last whisper.

Armor Items:

Frozen Heart- the best item with Armor for Blitzcrank. Gives the much needed CDR and Mana for Blitzcranks Passive but can be interchanged with
Randuins Omen- which is also a great item for Blitzcrank. Very Similar to Frozen Heart but adds extra CC and Health which can disable AD carries.
Wriggles Lantern- is the alternative to these two items. This item gives Blitzcrank much needed Sustain but falls off Late Game, It is a must for Jungling as Blitzcrank. I would generally buy this item first on blitz crank as sell it late game for a Frozen Heart unless i feel that I am carrying the team, therefore i keep this item and use the sustain to become more of an Attack Damage Carry rather than a Tanky DPS.

Magic Resist Items:

Wits End- never a bad choice on most Bruiser's but Blitzcrank does not need this Item
Force of Nature- A great item in General, Can be Interchanged for Banshee's Veil if i have bought Randuins Omen.
Abyssal Scepter- Is not a Bad Choice on Blitzcrank if your ap carry needs it against a high magic resist enemy team. This also is usefull due to Blitzcranks 1:1 ratios. When buying this i would steer away from buying Atma's and Infinity Edge and build more armor/magic resist related items.
Maw of Malmortius- is also another item to consider on an AD orientated Blitzcrank or you may buy this instead of Atma's if against an AP heavy team.

Blitzcranks Laning Phase is his weak point, that the opposition will probably try to take advantage of. If you play correctly, you can outplay the enemy top lane, depending on who they have picked.

I start off with Boots 4 potions if I am against an AP champion or a champion that requires a lot of farm who I can possibly outplay. If I am against a very aggressive lane I will start armor 5 potions to be able to sustain enough of the damage that they output so I will be able to have as many levels and creeps as I can before I return to base.

The best way to keep even with the enemy at top lane is to auto attack then instantly e them then auto attack again then back off when they go for last hits if they are melee. If they aren't melee your best chances of winning your lane is by farming to the best of your ability under your tower and call for early ganks. If you can land your hook in an early gank then it should almost always result in a kill. When you reach level 6 you start to gain some damage as your full combo actually provides quite a bit of burst damage.

First Trip Back you would want to purchase a Wriggles Lantern, Or at Least build into it.
This will give you much needed sustain in lane and makes it possible to be able to trade off more during Laning Phase. After building Wriggles I will decide to either build a Catalyst if their team is AP heavy or into a Phage which will lead to a mid game Trinity Force. If Catalyst is bought first finish your Trinity afterwards.

From Here start building your Infinity Edge as you will be quite tanky and can afford to buy more damage so that your late game will start kicking in.

After Infinity Edge you must decide whether to build more defensive or more offensive based on
both your team and the other teams team composition. For example if my AP mid carry is an early game champion such as Sion, and the enemy team has 3 AD champions I would go into an offensive Atma's Impaler so that my late game can make for Sion's weaker late game whilst being able to still tank their main source of damage. If my AP carry is doing very well and is strong late game, I would transition into my Glacial Shroud if i needed to fill a more tanky role for the team.

If the enemy team lacks hard magic damage, and I am required to be a major source of damage, I will build a Last Whisper after Atma's Impaler concluding my Carry Style Blitzcrank build.

If the enemy is quite strong in both magic damage and attack damage, i would then finish off my Banshees Veil and sell my wriggles to finish off my Atma's Impaler if i haven't already finished it or my Frozen Heart.

This is what i would generally do with Blitzcrank, but you may want to build differently.

Laning Phase should End as soon as you have finished Trinity Force.

This is possibly my favorite way to play Blitzcrank when it comes to Ranked Play or Tournament Play. Although my main accounts ELO is not very high ranging between 1350-1500, my win percentage with Blitzcrank is positive by quite a margin. Tournament Play is better for Blitzcrank since he works very well with a responsive team allowing you to make many plays throughout a match.

I always begin with armor 5 pots and ask my team whether or not they want to invade. If they want to invade I will not level up anything until I know where the enemy is. If we catch one out I would lvl Q and wait until they have flashed away before hooking. This is for experienced Blitzcrank players only. If the enemy gives you an easy hook by standing still not knowing where you are then just hook them at the beginning rather then letting your team catch them as they may flash to safety at the first notice of movement.

After invading and successfully gaining a kill or not, ask for a massive leash on Blue Buff as it takes too long to solo Blue with Q as your skill. If your team didn't invade ask for a pull on Blue Buff and spam e to clear Blue Buff faster. As soon as you hit level 2 off Blue Buff experience GANK! This is your best opportunity to pick up early kills for your team and snowball. After a few attempted ganks, either head back if you have made profit or clear your wolves -> wraiths -> red -> golems, then buy then gank again.

When ganking lead up with your e popping them in the air, do not open with a q unless you are brush ganking. After using your e auto attack them until they flash. Hooking them after flash determines whether you land the kill or not.

This may take a few practice games to get used to Blitzcranks jungle style but you will realize that your income will come from how good you are at ganking rather than farming the jungle creeps.

It is during this time I believe Blitzcrank truly shines.

At this stage of the game, objectives will become very vital in winning your game.
You and your team should start to group up and be looking for small or large team fights.
In this stage your team will rely on YOU to catch someone out of position with a Hook. Everything should be warded and everyone should be playing safe but with Blitzcrank you have the ability to be able to disposition someone. As soon as you have hooked someone a team fight should have started or your team should get a free kill which can let you do objectives due to having someone on their team unavailable to help.

When a team fight occurs your main job is to PROTECT YOUR CARRIES. This is not the hardest of tasks as you should just be spamming your e and hooking their bruiser or if possible their carries away from your own carries and towards yourself. Use your ultimate when necessary, remember it is a silence so use it to prevent damage upon your team if possible. A better scenario for Damage Orientated Blitzcrank is to separate one of their carries from the enemy team forcing a 1v1 with you. Usually if you can hook a squishy you can 1v1 them down quite fast. If you manage to win the 1v1 quickly rejoin the team fight to clean up or die/run if the enemy team wins the 4v4 which is not your fault if you have played correctly.

Blitzcranks play style is very unique and he is versatile in many ways.
I prefer to play the Tanky DPS Bruiser type Blitzcrank as i find it to be very stronk if played correctly.

I hope you learned something about Blitzcrank and would love to read feedback on what you liked/disliked about my guide to Top Lane/Jungle Blitzcrank.

Sorry for the lack of pretty pictures.