2 complex shaped materials in a mesh

Hi blender community, I like modeling cars as a hobby, but i have big problems when it comes to, for example a tail light that has 2 different materials, the clear plastic for the turning signal and the red tinted plastic for the break lights. I understand you can have two different materials in a mesh but as long as it follows the geometry you create and even then its not that accurate. But i mean to have two materials in a mesh without having to make the geometry to differentiate the two materials. I dont know if its hard to understand what I mean, to make it easier to see I have the following pic so you can see what I mean. Thank you in advance for any tips you could give me or refer me to a tutorial

For the best appearance you would model 2 separate parts like it is in reality. However you probably know how to use nodes to mix two material shaders (talking Cycles here, you say nothing about your choice) and you know that you can mix based on image mask. UV unwrap part, paint mask and use that for mixing - it won’t depend on faces then.

As you said, use the object geometry to apply multiple materials or you can uv unwrap the object and use a map to control the mix of two materials

Thanks Richard, im at work right now, but as soon as i get home tonight, im gonna try that. And yes, i am using cycles, before i was modeling mesh by mesh to apply a differerent material to each one, but with this i hope i would get better control.

there’s a tutorial in my signature, pretty basic stuff as long as you know UV mapping

That looks good, do you have a link to that tutorial? I know just the very basics of uv mapping…

the link to the tutorial is in my signature, but only covers the node set up. for UV mapping check the blender wiki or google search engine