I were bored so I took one of @RoadRipper 's saves, and with a big brush I placed some filter around the map of Great Britain made out of fuse, then replaced, AKA used the insert key, and replaced all of the filter and fuse with plutonium, and it immediatly shocked me. It looks like the map of great britain is still visible, and is embossed-like!
Strange, it appeared for me. Try doing it yourself. Open RoadRipper's Great Britain map save, use a megahuge brush ([ and ] help alot) and draw filter over it (no replace) then replace everything with PLUT, in fancy.