Can you design your own materials of a solar system to a given theme? Things you could collect / discover in this solar system. A new sword, armor or potion? Food or a drink? Why not entering the Materials Contest? Submit your very own idea as an image file. If you have a good design it could happen, that your idea gets added to the official game in a future update!
You could draw an image of the material digital, paint it on paper or handcraft it with whatever comes to your mind. Creativity is everything!
It just needs to fit the theme above!