yes, you can create them yourself.
NGUI has a texture packer included.
- NGUI => Open Atlas Packer => name your atlas and press create
- select your images (buttons, background, sprites) in the Project Window and press "Add/Update All" inside the atlas maker
- this will create the prefab where you can setup slicing etc for buttons
And also an font packer
- NGUI => Open Atlas Packer
- Drag in the font text file and the font texture (i using bmGlyph on OS X to create those)
- Name the font and press "Create the Font" in the Font Maker Window
- this will create the font prefab that you can use in your UILabel