Cosplay help please.

[pez]

I've made Faize's shorts, with elastic at the top and bottom, all hemmed and lined already. Because his shorts are puffy I allowed some extra material, but I can't get them to stay puffed up when I'm wearing them, so they don't look very Faize-y and the decorations on the sides don't look as good as they should!

So, I'm thinking about those puffy skirts with tulle (?) fabric on the underside. I've never made one of those, have no idea how to make it and have no idea if that technique can work here to make each trouser stay puffed. Anyone got any ideas?

(If there isn't a way, I suppose I will just stuff tulle netting down each trouser. XD)

Ah, I looked for "blue pvc" on eBay again, and this came up: not work safe. .........................okay...