iPhone 7 Superman Case

Superman Case remixed from AlexNeedsAName's iPhone 7 Case http://www.thingiverse.com/thing:1814855. It should be printed in Ninjaflex or other flexible materials like it with the back of the case facing down, i printed it with 3 outside walls but it still doesn't feel firm enough on the sides, comment if you print it with different settings and let me know how it comes out.