In this tutorial, I will show you how to make a procedural metal material using the shader nodes in Blender
Metallic
I will be using an oil barrel model I downloaded from Sketchfab
Add a new material and change the Metallic to 1.0
Change the Specular IOR to 0.8
Change the Base Color to a dark gray [#5C5C5C]
Add a Noise Texture node and untick Normalize
*NOTE: If you are using version 4.0 or before, use the Musgrave Texture node
Add a Color Ramp and connect the Factor output of the Noise Texture to the Color Ramp
Add a Bump node and connect the Color output of the Color Ramp to the Height of the Bump node
Connect the Bump node to the Normal of the Principled Shader
Change the Scale of the Noise Texture node
Move the color stops on the Color Ramp to control the texture
Change the Strength of the Bump node
To make dents, invert the Bump node
Roughness
To control the Roughness, add a Color Ramp and connect it to the Roughness of the Principled Shader
Add two Noise Texture nodes
*NOTE: If you are using version 4.0 or before, use a Noise Texture and a Musgrave Texture
Add a Mix Color node and change the Blending Mode to Overlay
Connect the first Noise Texture to the A Input of the Mix Color node
Untick Normalize on the second Noise Texture and connect it to the B input of the Mix Color node
Connect the Color Mix node to the Color Ramp
Change the Scale and Detail on each Noise Texture
Change the position of the White Color Stop to determine the Roughness of the material
Color
For the color, add a Color Ramp and connect it to the Base Color of the Principled Shader
Add a Noise Texture and untick Normalize
*NOTE: If you are using version 4.0 or earlier, use the Musgrave Texture
Connect the Noise Texture to the Color Ramp
Adjust the Scale as needed
Change the Color Stop colors on the Color Ramp [#4A2F2B, # 744040]