I made this simple phone case for about 2 and half hours.
Chain 38 stitches(Depend on your phone). Join the chain by slip stitch and make a single crochet for the whole row until you have the enough height that can fit the phone. You can also spice the project by adding up different color of yarns and embroider flowers (this design is not mine, I really love it). For the last row, Single crochet and 3 Double crochet for all the stitches.
Very simple yet so fabulous!