All Material mixing

Blender Development Fund
Asset Library
Blender Development Fund
Asset Library
Easy Mat Blend – Automatic Raycast Material Blending
$6$4.20 Dev Fund Contributor

Blender Procedural in Addons

Pbr Mixer
$28

Nodes and noodles in Surfacing

Master Material Mixer
$15 Dev Fund Contributor

3D.SPACE in Surfacing

Color Ramp Converter
$9 Dev Fund Contributor

David Elek in Addons