Perfect binding is one of the most commonly used method of binding for a thicker book in commercial printing. This method can bind from 2mm up to 50mm thick,
Basically it is a printed cover wrapping around the text and bound with glue, a professionally bound book can be produced in seconds once setup.
To make the book more special, embellishments like foil and spot UV could be applied to the cover, binding with flaps also available as a premium option.