Martin, Thanks for all your work on this excellent project. Getting same error as Franky when I try to create the pdf using categories. The following is returned:

Fatal error: Cache folder inexistent or unwritable. in /var/www/domains/…/docs/wp-content/plugins/make-pdf-newspaper/NewspaperPDF.php on line 2019

Using WP ver 2.9.2. Have created cache and set to 777.