[sebiol]

Disclaimer: don't have TikTok so didn't checkout the linked source.

But on the topic of a non-engineer building a tunnel, there is also Colin Furze on Youtube [0]. Building a tunnel under his house to connect his 'bunker', workshop, home and future udnerground garage.

[0] https://www.youtube.com/watch?v=YOelRv7fMxY&list=PLGjbAdaOBL...