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How should I do this?

So I consider myself decent at photoshop however this design has thrown me for a loop as to how to recreate it. I mainly skin racecars and I'm trying to replicate this skittles tube/flag banner. Right now Im sorta stuck where i have it as i use a rectangle with an inner glow of black and then very thin white rectangle over top with an outer glow to replicate the tube shadowing however this only works for the beginning and not when it starts getting wavy and the shadows dont condense relative to the size of the tube.

Ive basically reached my talent level with this one and need advice on how to go about it.