This is a tutorial on how to do a crocheted, fabric lined mobile phone cover. You need:

• about 30g of wool (I used sport weight cotton) a crochet hook fitting the yarn (I used a 2,5mm hook) Fabric to line the case a sewing machine or patience needle and thread fitting the fabric and one fitting the wool a button

Crochet two rows in star stitch (there is a good YouTube tutorial on this stitch) to find gauge, always comparing it with the device it should fit. For example: if one full star in your gauge is 1cm wide and your phone is 7cm wide then this obviously equals 7 stars. Now add two more stars to cover the sides as well. If one star in your gauge is less then 0.6cm then add four stars instead of two.

You find the complete tutorial here.