[Material/Dop] material density

research for material density
https://www.engineeringtoolbox.com/

[ref-Material] Free HDRI

https://hdrihaven.com/

[ref-Material] Metal materials study by texture artist Jarrod Hasenjager.

Metal materials study by texture artist Jarrod Hasenjager.

https://www.behance.net/gallery/35636521/Material-Studies-Metals

[ref-Material] IOR list

https://pixelandpoly.com/ior.html