I'm a big fan of hard-edge details like studs and metal tips. Ever since I first saw a collared shirt with metal tips, I knew it would be a fun DIY, but I wasn't sure quite how to do it until I stumbled upon these decorative corners in the scrapbooking section of Hobby Lobby the other day.
They're made to embellish the corners of scrapbook covers, but it's easy enough to add them to fabric instead. I used a small pair of pliers to open them slightly (but, if your shirt is made of thinner fabric than denim you won't even need to do that) and then used a hammer to squeeze the corners down on the collar. What could be simpler?