Tinted glass.........

Can any of you experts out there help me?

I'm making up a resin kit at the moment - a Team Slot Lancia Delta S4, but with a fair few changes to make it look more like the original. I want to put in a tinted (fairly dark) rear window (this was solid resin on the original kit) but I'm not sure where to source some tinted plastic to make this from? Anyone spotted suitable packaging recently??

My other option is to somehow paint/tint some clear plastic but I'm not sure how easy this would be....or how effective it would look.

Any advice or pointers much appreciated!

Thanks

Don