Hi gvee, welcome to our Blender community, I’m not sure I understand you correctly. You choose the UV channels here: Select Object Data Properties> UV Maps> camera symbol (only one at a time).
Under UVMaps I only have one UVMap. There is no hand, foot face, etc.
So in order to export a UV layout of other material groups, I have to create a UV map? I don’t understand. The OBJ has the UV data in it, why do I need to create a map?
Guys. I don’t need udims. I need to export a UV layout of all channels. When I click Export UV Layout, it should give me an option to export all UV channels.
SOLUTION: I ended up exporting the OBJ to another 3d program and from there I was able to easily export the UV layouts of all channels. Any 3d program can export UV layouts of all channels quickly and efficiently when you click it’s export option (except blender, which makes this process extremely difficult and cryptic).