Using vinyl on mods?

So the other day I was watching customization videos to see if I could learn anything new and the person cut a hole in her doll's mouth and used the leftover vinyl to form the new lower lip with what I think was a heat tool? It was really cool, but also in Japanese and my Japanese is not advanced enough to understand what was being said. Does anyone know anything about that method of modding? Are there any videos on it in English or with subtitles?

I think its used using either a soldering iron or heat pen!

This channel has videos with subtitles!

Oh that's cool! Thank you for the link!