/cgl/ - Cosplay & EGL

As someone who doesn't actually work with clear materials for crafting, can someone give me an idea of how I'd begin on Kana's vial case? Should I go with tough plastic sheets and maybe heat it into form or maybe sacrifice stiffness to use vinyl ala ita bags? Is it even possible to stiffen vinyl without it being visible? I'm aware I'm probably coming off like a complete knob but I'm actually stumped.