The question I have about this is not about how to create them, but how do you apply your decals to the edges? Are people using some houdini stuff or is this really done manually? Is there any trick aside of copying faces and then adjusting the UV?
Houdini would be the fastest way to be honest, just detecting all edges with nothing within a certain range and placing them there. However, placing a chamfer or a couple of edge loops on each corner and then duplicating/split would still be a good method even better if you could just script that in your DCC to take the…