Looking to create a Sky Block from OpenBlocks style block for 1.14.4

I was wondering how to render an empty skybox through a block in a similar way to OpenBlocks 1.7.10.

Example : https://www.youtube.com/watch?v=WooemEN00BA

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Also quick question: What entity is passed when the blockbreak event is called? Is it the player entity or the block that was broken?