This is my first guide to a charakter i have a lots of playtime on several accounts and a few weeks ago i came up with this for me unseen build at the time.
Before i go on what this build is about it has to be said that there are A LOT of runes kennen can take and in a lot of situations and matchups you should take one of them (clepto, aery, phase rush, electocute) but out of fun my build showed actual viability for me so here i am.

Why should you take this build ?

GOOD QUESTION
with this you can lane against champions you will need a lot of sustain against and just building a gunblade like the pros do didnt seems worth to me so i decided to put some extra use to this item
plus your second item the spooky ghosts give you vision and another 2 freeze rays
you at the end you gain damage, sustain, better cc and cooldown reduction plus the components of gunblade are both good for kennen and the ghosts are really cheap

You will be able to play the early game like you would with protobelt with revolver or if you want the sustain ad and first freeze ray you can switch to cutless and bully your enemie with autoattacks
after you hit your 2 item spike look out what your team needs and provide that with your next items
use your items to facecheck bushes, catch enemie out of position or burst targets down in teamfights
you will however miss the mobility and waveclear with protobelt so watch out where and when you engage
i would recommend to try it out in a normal first its a different experience to the normal kennen playstyle

if you like this build, have success with it or point out some points i missed feel free to tell me