Hi guys,
I'm new to the armor scene and kind of new at modelling in general. I've decided to start my first tank and chose a British Challenger II the trumpeter kit, now I have a question about painting a certain area of the tank. I don't know what these are called exactly but they seem to be lenses. I've included a picture so you'll know what I'm talking about. What would be the best way to go about recreating these? Thanks in advance!

There are different ways of doing it.

There is a mylar confetti that has the color shifting properties similar to the coated optics on modern AFV's. This confetti can be found in craft stores.

Another possibility is painting the lenses with alclad prismatic lacquer paint.

Another way was using gloss black with Tamyia clear paints IIRC.

I have recently tried a new method, with does not look too bad. I first paint the lense with Testors Chrome enamel, when dry I apply a coat of Vallejo tranparent, ie, blue or red.

I do the same as Kevin (above), but I use an undercoat of black, then a couple coats of tinted clear (red, blue, or green; depending on the effect I am looking for) and then a couple coats of clear gloss. This gives it depth and reflects the light just like the real lenses do. It also will change color from different angles like the real ones.

thanks guys for the quick replies! I'm going to try that gloss black with the clear colors on top