There are literally no items that modify someone's attack range, for obvious reasons, but I submit this idea to you:
Sniper's Scope
Build path: (
+
+210g) OR 1485g
Type: active, ranged only
Cooldown: 70 seconds
+30 AD
+8% crit chance
Active: increases a ranged champions attack range by 300 units for 4 seconds.
Sounds like an interesting concept, but I have a feeling champs like 
and 
could get too stronk with it. Especially how Koggy already has that massive range increase on his W.
Beyond stupid idea. All ADC would build it and go hit other players from outer space. 
is already long range sniper and you wanna give her more range? Shame on you.
They are actually adding an item called Rapid Firecannon, which charges like Statikk Shiv, and at 100 stacks, increases the range of your next auto. So uh, yeah. Riot already thought of a way of adding it and they're doing it.
