Some quick thoughts on zac. These would be fun, A lava skin, since lava is somewhat liquid like.
And also for this winter season "Figgy Pudding Zac" or "Fruit Cake" one of those Jello inspired creations with stuff suspended in it that no one ever wants to eat. When you hit him he could drop little things that would be found inside of him rather than just blobs XD (you know small fruits, or whatever)
Yea, it's a good idea. hopefully Riot will ever do it! Please visit my thread where I suggest a new skin :) I'd be more than glad if you would comment :) http://boards.na.leagueoflegends.com/en/c/skin-champion-concepts/EEJ71AGd-skin-concept-light-bringer-jarvan-iv-related-to-sion-reborn
Considering the Big Hero 6 movie released earlier this year, maybe we can have a 
skin based on micro-robots like Hiro created?
Some kind of Mecha/BattleCast/WhateverRobotic Zac made of tiny machines that disassemble/reassemble...
