You can tint the MV lenses with Tamiya clear paint. Available in red and amber for sure, not certain on Green. Also Micheals crafts has a small jewel that actually looks like a fresnel lense sutable for class and markers in 1;20.
If you want them for marker lights, you might take a look at LED covers. They come in red, green, yellow, amber, blue, and clear. They're translucent, so the light shines through and they look like little Fresnel lenses.
Fake stained glass paints are transparent and are colored with dyes rather than pigments.
The color is fairly saturated for a thin coat.
They are available in small bottles at craft stores.
Stinky nail polish type stuff - Ventalation required !
Existing clear lenses could be colored with a coat or two on the inside/outside and refitted.