Here is my first (extremely short, bad and useless) tutorial on how to make a solid colored part which isn’t affected by lighting and which doesn’t use GUIs (not fully clear behind a transparent part) and which doesn’t have the neon glow around it.
Your final result may look similar to this:
Select any part you want to make solid colored. Make the material Forcefield and make the transparency a negative number such as -100. You will now have a solid colored part. It will not be affected by lighting in any way. I don’t really know why this happens, but it’s probably because the forcefield’s fresnel effect gets bigger the less transparency there is, and -100 probably makes the fresnel big enough to make it completely solid.