I'm not really into phone cases for protection because I don't drop my phone much, but I love having crazy designs on my iPhone. Here's any easy DIY solution that you can make at a low budget and with open creativity.
I started with a bright green case that I got from Radioshack for $6. I'm pretty sure you can find a bunch of these in your favorite colors on eBay, which I plan on stocking up on! The studs were found at Michael's in the stationary section. These studs all came from the same pack for $4.99 and already have strong sticky adhesive on each one. You want to make sure to eyeball each placement of the stud so that you are able to fit them on. You can literally place them anywhere to your liking. I personally wanted a full studded case with the green still visible (which I picked because to follow the neon green trend!)
I plan on making more and possibly selling them! Stay tuned and enjoy your DIY!