This is a basic showcase of how to create a "Ghost Cube" Ghost Cubes are currently being used multiple times throughout runs in the Any% category Here's how it works, and how to create one:

To create a Ghost Cube, you have to stand in a position where placing the cube normally, is impossible. This is shown ingame by the "marker" for the cube you're holding, turning from blue to red.

Once you're holding the cube so that's it's unplaceable, you need to hit the button to "respawn" the cube AFTER a short delay of picking up the cube in the first place. This will spawn a Ghost Cube for you. (It's worth noting that hitting the button TWICE quickly, will spawn the Ghost Cube immediately.)