For the necklace pictured above, I used a round metal shoe clip, but there are so many different styles of decorative shoe clips available that it shouldn't be a problem to locate one or more that you like. Shoe clips were originally sold by the pair, so it's very likely that you'll have to buy a set of two matching shoe clips.
As for a chain for your new pendant necklace, you may already have one that will work for this project in your jewelry box right now, but, if not, they're available at most stores that sell costume jewelry. You can also buy chain by the foot at your local crafts store and then add a clasp after deciding on the length you want. Then simply clip the shoe clip to the chain.