Introducing: parametric ISL shaders.

A freshly milled aluminium. nk reflectivity is dimmed by one third.

The following controls are available to the user in the bump shader editor:

paramBumpMult:
Carving depth.

paramScaleUV:
Tool scale.

paramRings:
Tool shape (approximative furrows count, also offsetting the random shape).

paramVariance:
Randomization of the milling coordinates.

paramNoisy:
0: sinusoidal tool shape, 1: random tool shape.