Generate Mesh Spline from GameObject

[processor]

I have tried mesh extrusion before but couldn't get the result of the rainbow because I can't use a texture alone to define the colors of the rainbow for the created extruded mesh. That's why I have created a rectangle in Blender and sliced it into 7 parts and mapped each part to a color. Now, how can I apply the same colors (with the same order) of my rectangle model to the extruded mesh? I want to get a road with the same rectangle I have created.