What is Pixelator?

Pixelator allows you to dynamically create textures during datagen.

When should you use it?

You can look at my other mod Tool Progression Overhaul.

In that mod, I used this library mod to generate tool and armor textures.
On the github page. You can even download a directory full off templates, which are just iron tools with the right naming.

How to use this mod?

On the github page it is explained.