Merlin Mystery Solution: Part 6

Golden Merlin Symbol: GMer
Go to the Merlin Mystery Solution Index.
This is Part 6 of my solution to The Merlin Mystery by Jonathan Gunson and Marten Coombe.
This post provides the complete solution to the Cube mini-puzzle.
In part 3, we established the chain of objects that links the Cube to the Merlin symbol (“Mer”). Then, in part 5, we resolved the ambiguity between the Cone and Cube both linking to Mer. The Cube links specifically to the Gold and Silver Merlin symbols, “GMer” and “SMer”.
Once solved, the Cube puzzle is a major leap forward in finding the 75 different border squares which “spell out” the final solution.