This is not an original addon, just a port to the 1.21.1. You can find it at https://modrinth.com/mod/create-molten-metals . While being a port, this mod also adds better compatibility with other mods, unlike 1.20.1 version.

Do you have a Tinkers' Construct shaped hole in your heart? Why not fill it up with some Molten Lead!

Create: Molten Metals is a lightweight create addon with one goal in mind: let you melt down metals and and pour them back out into ingot molds. With a significant (and ever expanding!) list of compatible mods, this is the best place to go for modpackers looking to create an expert experience through the power of Molten Metals.