Setup 64 balls as an object to see the effect of metalness and gloss values in PBR texture and shaders.
No materials such as copper or ceramic, or plastic. Just UV color map and the rest of the maps below.
Each ball is mapped to one of the 64 squares on the color map. Just for info purposes only.

Here are the maps I used.
Color Map:


Gloss Map:


Metalness map:


Normal Map:


I set them in the map editor as follows.


Here they are in test game.





Below is a dropbox link to the files to check out the results yourself. I scaled the 64 ball object in the editor for effect. You can scale them anyway you want. Change the skybox and terrain texture and see how it works. Notice that normal roughness matters also with the gloss and metalness.

https://www.dropbox.com/s/r4utaxc4jaskvsu/64_ball_GG_PBR.rar?dl=0

great test, however looking at t-bone's slenderman in PBR has made me realize that you won't like the results so much were this object placed indoors

That is correct, things look different indoors. But you can add your own cube map to objects using the texturename_cube extension and the object will have that map on it, instead of the skybox and terrain.

Right now you would need to take the 6 shots inside your map where you wanted that reflection. Then make a cube map out of it in GIMP Nvidia plugin or Photoshop Nvidia plugin.

I see that Preben put Lightprobes in Game Guru Loader, so there is hope we shall see them in Game Guru also.
Get that, and lightmapping working again with static lights, and we should be in decent shape for some nice scenes.