This Quicksilver costume from Days of Future Past was a personal project that was a delight to make. While many elements were purchased, I created the faux leather jacket from a very heavily modified pattern, and the belt pouch and both Stereobelt units from scratch.
The Stereobelt was a challenge, since the only images available are fairly low resolution and hard to make out. I worked with what I could find, though, and created a 3D model in SketchUp, which I later 3D printed and hand painted.
You can check out where I found all the other components, including the actual shoes worn in the movie (which I bought) and the actual watch (which I didn't - it cost $900!) on my Pinterest.