Creating a "sky block"

[knotty ivy]

I want to recreate this https://modrinth.com/mod/block-of-sky mod but for 1.21.1. I've added the block itself but can't figure out how to render the skybox onto it

[hollow wigeon]

https://github.com/LuminaSapphira/block-of-sky/blob/1.20/common/src/main/java/net/cerulan/blockofsky/client/SkyBlockEntityRenderer.java

https://github.com/LuminaSapphira/block-of-sky/blob/1.20/common/src/main/java/net/cerulan/blockofsky/mixin/common/LevelRendererMixin.java