@m Thanks Marcel ! We had the chance to go to a screen printing shop in our neighbourhood, that is called Turboformat, and the very kind and talented guy that works there (Ben Sanair) explained to us how to proceed, he helped in the process to expose the printing screens, and then we went for hours of screen printing by ourselves ! It required precision and long-term muscular effort ! It was half a day for 150 CDs and another half a day for 100 vinyls