I made a shaderball to work with material creation, I think it can be used to show the parameters of the principled bsdf.
here are some examples.
Metallic Parameter
Roughness
Alpha
Anisotropic
Subsurface Weight
Subsurface Scale
0.0, 0.05, 0.1, 0.15, 0.2
Subsurface Anisotropy
Transmission Weight
Coat Weight
Coat Roughness
Sheen Roughness Parameter
Also I made a comparison of AGX vs Filmic with a carpaint shader.
Everyone who want to use this Shader ball
Here is the blend file, it is available under CC0 licence now.