Riot said it was hard to make the particles for Zac, etc so that making a skin for him wasn't easy, so doesn't Storm Zac makes it easier? instead of a blob he is smoke, it's easy to de-attach and re-attach and it's a whole different texture than a recolored blob.
https://www.youtube.com/watch?v=FmFeODvZAIY
in the meanwhile, Hades 
It's less that it's hard to make particles for Zac, and more that it's hard to alter Zac's animations, which any skin that wasn't "a blob of something" would have to do.
So you could put a smoke texture on him, but he'd still look like a congealed "blob" of smoke.
I think you'd have better luck with maybe putting on an animated texture and having Magma Zac.
Zac really needs a new skin! I understand that creating a unique skin for him is pretty hard due to his model and how he moves,however I think riot should try to push the development of zacs new skin higher up in the priority list
<3 zac
