So my teachers asked me to give them some of my models, with the corresponding textures, and they were asking me to send them rough, metallic and ao maps (and height when needed). Instead, I prepared what many people call RMAH maps. That's why I prepared this video. I haven't seen much information about it online so here it is.
UE4 gives you full control over the channels (r,g,b,a) of an image. So if you store different maps, into different channels, you can break down that image and plug the red, green and blue channels separately.