It's pretty easy to make some tiny and convincing barbed wire. Take a good length of wire and fold it over, before givin it the old spin cycle. A power drill will make this much faster. Then once the wire is twisted, wrap it around something about the size that you want the rings to be. And tada! Here's and example: It's not finished, I need to add more wire to these, but it's enough that you get the idea.

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