opaque acetate...

Does any one know any suppliers of these, or a different material I could use? I need somthing thin, 0.1-0.2 mm can be easily bend round a raidus of 12mm and is opaque. The part will be sliding in a track, with no load on it…like a shutter for a optics experiment

Ohh, I just thought of a polyester film instead…or maybe a bit of spring steel, though I guess that might be hard to stamp in to a shape?