I just rounded out the back of the original thing and scaled it up 33%, so as to use it as a costume prop.
I originally remixed this for an Alice in Wonderland themed Mad Hatter's Tea Party. I can imagine using it for various other costumes.
I found it impossible on my printer to make the detailed pieces from the original in order to have a raw plastic multi-colored pocketwatch (though the glow-in-the-dark hands and numbers on one of the photos on the original reallllly appealed to me), so I stuck with the single print version in white.
Then I took a hobby knife and sandpaper to my white plastic pocketwatch in order to smooth it out, and sprayed it with gold. Then I had a 13 year old with patience and a small paintbrush paint the face of it.
Then, in order to preserve the paint, I sprayed a coat of clear, gloss enamel on it, which unfortunately made the gold less shiny. :-( Oh well, you live you learn.
One could use a real chain to make it look more realistic.
I just used some shiny gold elastic and a safety pin.
I may have once received the elastic wrapped around a present. I'm a pack rat.
I used Sketchup to add the rounded off back, and made very few other changes.
The STL mesh was pretty well mangled by being imported into SketchUp, though.
I did not have the patience to manually clean up this well detailed model inside of SketchUp, so instead of insisting on creating a fully solid model, as is my usual goal, I relied on Netfabb's Basic Repair tool to repair the STL after exporting it from SketchUp.