How to remove a GUI model and replace it with a .png

[zealous temple]

Examples:

1. A .png GUI icon
2. A model GUI icon

Instead of the model GUI icon I want to use a simple .png

[proud jolt]

You could add and use this shader in your resource pack (you can find instructions and an example pack in there too):
https://github.com/ShockMicro/CorePerspectiveModels/

[zealous temple]

Well this is going to be hard