This is a smartphone case for the Samsung Galaxy S8 with the Solar System on the back. The planet and sun diameters are drawn to scale, though Saturn's rings are somewhat flattened to keep the case functional. The planets can be printed in a different color for contrast and then glued on.
Another option, if you prefer to keep a flat case, is to just print the body and omit the planets. The case looks great with just the the silhouettes as well.
For printing the case, I'd recommend a filament that's somewhat flexible, otherwise it could break while fitting it onto the phone. ABS or some PLA's work good. I did not give the holes for the planets any margin, so it might take some filing to make it fit, but I preferred that over the chance it would be too loose.