Some shaders benefit from the ability to use random values. Each Material has a few nodes that can help add randomness to a shader. Randomness from a Perlin noise texture can be used to generate interesting-looking materials such as marbled materials. The noise can also be used to drive bump maps, height maps, and displacement fields for some neat effects.
Choose a material to which you'd like to add some randomness. Open the Material in the Material Editor, and follow the steps.
Insert a Noise node into your Material Editor window.
Normalize the coordinates of the object you're adding the noise to. You can use math such as the following to do so:
Subtract the minimum from each processed vertex in the system to take the object to sit at the origin.
Divide the vertex by the size of the object to put the object in a unit box.
Multiply the vertex value by 2 to expand the unit box from 1x1 to 2x2.
Subtract 1 from the vertex values to move the unit...