This is a super easy and very cute DIY.
All you need is:
Hot glue gun
Clear silicone phone case (find them on ebay)
pom poms (works best if you have a selection of sizes)
It's just a case of sticking the pom poms on. Work quick as hot glue dries fast. Also make sure you have some small pom poms to fill in gaps. Once it's all dry add glue where needed and then put some around the edges of the case to make sure the pom poms stay put. I also have a pop socket on mine so covered that too.