I have been asked a few times about how I make my razor/barbed wire for my futuristic figure bases.
This is not the most realistic I have ever seen but it is certainly the easiest.
Floral wire is the only material you'll really need for this one.
Once the glue is dry, wrap your wire braid around something that will give you the correct scale. I used a paintbrush handle. For smaller scales, wrapping around a toothpick might be a good option.