Hey guys,
I am bringing you my first guide!
2 Ways to build Jayce on TopLane and BotLane!
So let's get started!

Nothing really special here !
My Top/Bruiser guide delivers the most main Bruiser AD runes you usually see. Abit of damage and some resistances, which you try to build up for the lategame in your itembuild.
Nothing much to say to my AD/crit runes!

Bruiser Items: Well you gonna build straight up defensive! Triforce makes Jayce powerfull enough to carry throughout the whole game. The good amount of 3k HP will give you enough for your Atmas and Maw to be usefull and do a good output of damage. The resistances will not just make you a bruiser, i'd even get that far, that you can call yourself a high dmg output tank!

Crit Items: I think these explain themselves just by being listed.

Well its quite easy.
The Mercury Cannon's "W" skill "Hyper Charge" on level 5 does 3 quick shots of 130% of your AD, which can actually crit. So lategame you deal in matter of seconds more than 1,8k damage (depending on armor).

It's easy and plain and i hope you can follow my trail of thoughts and find the idea appealing.
As i don't feel like explaining how to play jayce, but still can do on request ;)
Have a nice day and game on!