This is an all-in-one tool for SM64 Hacking.
Create a complete SM64 ROM Hack with this tool and a 3D modelling program.
It has brilliant features that no other tool has as easy as this.
If you want learn more about this tool, checkout the public notebook.
Thread on Hack64
This tool is for creating hacks with custom levels, not for editing or even keeping vanilla levels. Because the many features it is possible that a few vanilla levels doesn't work anymore as expected.