So I thought I'd make use of the things I have lying around the house then I dont have to wait for it to arrive and I could get on with my prop that same evening
It's a very simple and easy technique that I hope people will follow and use in the future.
Step 1: The Materials
String, roughly 2.5 times more string than you want barbed wire.
PVA glue, the staple of many a project
Grey Paint, I used grey poster paint, actually white and black mixed but anything that will mix with the glue will be fine.
Make up a pot of glue. I diluted mine down 1:1 with water, which means it dries softer and is easier to work with. I mixed the grey paint into the glue at this stage to ensure nice even colouring. Roughly 4:1 is my ratio of dilluted glue to paint.
Step 2: Making the wire
Now comes the trick for the wire. Carefully fold the string in half, it should start to twist around itself because of the extra twists you just put in the string. With a little nudge you can place these twists evenly along the length of the string. This will form the base of your barbed wire.
Next you need to dunk the string into the glue, make sure it is covered all over and none of the string shows through the glue. The best way to do this is just to accept you're going to get glue all over your fingers and enjoy it. Hang the string up to dry, or curl it up on a surface, just make sure it isnt touching itself or you'll have a gluey mess.
Step 3: Making the barbs
Once the barb has dried completely then cut the ends at an angle to give it a pointed look.
Repeat this process to place barbs at your own preferred spacings along the wire, before you know it you'll have a long section for your own project