Invisible, untouchable blocks

[Snaxle]

Some blocks are invisible and untouchable, so you can only see them if you hold a tool.
I do not know how to make them, someone tell me please.

[Ad Bot]

[Regulith]

Uncheck the rendering and collision boxes on the wrench menu.

[Deriboy]

Uncheck the rendering and collision boxes on the wrench menu.

Then click send