If I understand well, you want to create a book with rounded irregular shapes, is that right? First, you need to create theses shapes on “standard” pages, then fill these shapes with the colours you want to use. Then, you must indicate that theses shapes mut be cut off. So you need to:
- create a color that you will name “die cut”
- define that color as a spot color. You can use a dark color (black is good) to simulate it
- create shapes with a stroke using this color and place these shapes on a separate layer, over the artwork layer
- do not forget to set the stroke as overprint to avoid that the stroke knocks out the underlying shapes
- and the most important: speak to the printer/manufacturer