Barb wire for the top of fences

I just use sewing string. I paint it silver with a brush and it looks like barbs. You will also have to get some wire to act as the bent post to attach the string to.

Use ca glue with an accelerator to put everything together.

alan Graziano

Try the military model aisle.

For example: https://accurate-armour.com/ou...ion-products/ff76015

I understand that this guy did this for H.O., but it sure looks awesome.  With a little adjustment in the gauge of materials involved, I believe you can successfully reproduce this in O scale.  

https://www.youtube.com/watch?v=0_guMOYoCpw&t=59s

I plan on trying it eventually.  I am still installing track and switch wiring for sidings and my yard.  My mainline and the signals are wired and I started doing some ballasting on it to mix up my activities.   

I hope this helps.

Bob

Thanks everyone for the ideas.....Paul