I have people downloading my designs multiple times per day, but it seems that very few users are remembering that feedback on designs, their printability and just plain posting their prints is an integral part of the “Community”. I think it would be nice to provide the user base with a regular gentle reminder to provide feedback.
Maybe provide a monthly email with links to the designs they downloaded that month asking for ratings/feedback might be a gentle way to help improve design quality, as well as to encourage more people to actually try to create content and become more integrated into the community.
Just a thought