Hammered gold, or a “hammered” look in general can be a very charming and desireable look, as it gives a feel of something handmade and naturally worn. It is also applicable to give objects an antique look.
There’s a nice article discussing a hammered gold shader using Blender and LuxRender here: http://www.luxrender.net/wiki/Gold_material, however not everything was easiliy transferable to RenderMan for Maya.
Though this article is based on RenderMan 21.5 for Maya, it should be easily modified for any application using RenderMan.
Looking for tips on how to create a hammered look often describes the use of a voronoi texture, and the first option I tried was indeed to use the PxrVoronoise node, though it quickly became clear it wasn’t going to give the desired effect.
Instead, the PxrWorley node turns out to be perfect for this type of effect!
I think the effect may be a little over the top, but I thought it would make it clearer what the effect looks like. But toning down the bump will give it a more natural look.
The top left texture is the PxrWorley used for bump, and the top right is the PxrVoronoise used to add a slight feel or dirt by applying it to the specular attribute. The material used is a standard PxrLMMetal shader, using the Gold preset, a Roughness of 0.400 and a slightly lowered value in Extinction Coeffiecient to give it a warmer color. Below is the shader network for reference:
For lighting I used a simple PxrDiskLight and an HDR from NoEmotionHDRs called “04-23_Day_C”, which you can download from http://noemotionhdrs.net/hdrday.html.
Download the Maya scene here hammeredGold.ma. Made in Maya 2016 Extension 1 SP6.