It's a purple room off of the giant throne room in the sky warp zone with a platform that has six purple crates and a pillar with two columns of five box symbols.

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It's a purple room off of the giant throne room in the sky warp zone with a platform that has six purple crates and a pillar with two columns of five box symbols.
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That room is showing unfolded cubes (called nets) in 2 dimensions. There are 11 different ways to unfold a cube and only 10 shown on the pillar. Here are the 11 cube nets:
Lay the blocks out in the missing 11th way. |
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Use the six cubes to make a Z-block. See image below:
This last setup is the last/11th (unpictured) way to unfold a cube. |
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