As a Zac 
main it's frustrating that there are so few skins to choose from, and since he is a blob of goo there is SO many things you can do with him. The most obvious (and coolest) would be Liquid metal Zac, think Terminator 2. But there could also be thinks like Molten Lava Zac where he is, well, Lava. Or Plasma zac made completely of energy. Or even Ghost Zac. There are so many more ideas but i think you get the gist of it.
Leave other skins below :)
flyingbaklava2 votesI am with you there my friend! Zac needs more skins and he has so much potential for cool skins. There are already champions with double digit skins. It is about time Zac got a third skin.
MysticMoto3371 votesAyyy the Zac god himself! Hi Tomer
WhiperSnapers2 votesMolten Zac would be amazing
crippler381 votessnow slush zac, it'd be a white sticky goopy zac that knocks people up and gets everywhere really quickly. Randomly spurting in slushy white goo when using abilities of course.
MysticMoto3371 votesSnow Day Zac would be really awesome! I never even thought of that one
Tamur1 votesZac isn't the only champion that has this problem. Yorick mains(not sure how many are left) have waited 3 years for a skin before they were told he wouldn't receive another skin until his rework which 2 years later is finally happening.
It takes 6 - 8 months for a skin to be made. It's even longer when a champion has to have more than a single model made and textures (ie Zac due resize feature and his current abilities)
The Skin are hard at work making sure that skins come out right or at least descent enough to be sent into the game.
MysticMoto3371 votesI agree completely it's just annoying to see champions like Ashe, who already have so many skins, getting new ones and some champions like (not limiting to only) Zac never get them. I think every champion should have more skins but the ones with less skins should be the priority
GULAG 4 U1 votesgolden zac
white zac
Black zac
chroma zac
Sukishoo1 votesSure there's a lot of things they can do for a character like him but at the same time it takes them a lot of work due to the way his model is and abilities work. I'm sure he'll get his next one soon enough but it will take some extra time.
SPOOKZ3081 votesa cool one would be candy zac or sugar zac