You can bake nearly any map as emit bake type in Blender. There's nothing special about albedo, roughness, metallic and the majority of other maps, so just plug your metallic into an emission node or directly into the material output and it'll bake fine. You can also use plugins like ucupaint to make the baking process…
https://archive.org/details/mayatechniqueshy0000mill/page/n3/mode/2up it is scanned and you could officially borrow it digitally if you are applicable. the book goes over more parts than just modelling like texturing, skinning and rigging. For modelling only, you could also peek into the powerpoint file accompanied with…
still got and use my 2004 library of grayscale grime overlays.... various photoshop blend modes and a touch of colourization can produce interesting effects they would normally used in conjunction photographic reference. the strange thing is they were pretty big images for the texture limits of the day 2048 * 2048 so they…