Will there be a mac build at some point? I want to use it but all I have is a mac :(
Unfortunately I don't have a mac, so I cannot create or test a mac version yet.
You could still get the Godot game engine and Material Maker sources from Github and run the tool directly in Godot.
1. Download the Godot editor and export templates from https://godotengine.org/download (standard, not Mono).
2. Download the Material Maker source code and extract it: https://github.com/RodZill4/material-maker/archive/master.zip
3. Start the Godot editor. This opens the Godot project manager. Use Import to select Material Maker's `project.godot` file and edit the project.
4. Install the export templates TPZ file using Editor > Manage Export Templates... > Install From File... at the top of the Godot editor.
5. At the top of the Godot editor, choose Project > Export. Create a preset for macOS (more information). Export it anywhere on your filesystem.
6. Extract the generated ZIP by double-clicking it then run the generated .app bundle.