Preface: This special issue contains selected papers presented at the second edition of the International Conference on Direct Digital Manufacturing and Polymers held in Marinha Grande, Portugal. The conference is heldbiannually and takes place in India(University of Karnatak)and Portugal(Institute Polytechnic of Leiria)on an alternating basis. In 2017 was held in Marinha Grande, an important industrial area of Portugal and home of the Centre for Rapid and Sustainable Product Development, Institute Polytechnic of Leiria. The conference coincided with the 10thanniversary of the foundation of the Centre and a special celebratory gala dinner was held at the Hotel Mar e Sol. Director of the Centre, Professor Nuno Alvespresented to ProfessorPramod Gai, the Vice-Chancellorthe University of Karnatak, the “International Institutional Collaborator2017” award. Other awardswere presented and the Director, Professor Alves acknowledged the strong support received by CDRSP from the President of the Marinha Grande MunicIpality.