If I had a design challenge of course I would join and participate in an online community, for example I would use Facebook, because that is the main online community that I have been working with. From my point of view Facebook is the most important online community, because a lot of people in the world use it, and you can find any kind of person, from almost any age, with different interests and different points of view.
For my design challenge, first I would find my target group, and after that, I would upload pictures or videos about my ideas so I can get feedback from the people interested on my design. Also I would put tests and questions so I can know everyone’s opinions and preferences. After seeing the results is going to be easier for me to be done with my design because I am going to know exactly what my target group wants.