I think baler twine would work real good just make it so nothing larger than say a song bird can get through. some even hang old CD's off of it . I bought predator tape it is very shiny and crackles when the wind hits it and the light bounces off of it. My area is half and acre so I hung streamers from tree limbs and around the house we went from tree to tree and hung a few that way. But I think for an enclosed run your idea might be better. Just make one run going length wise then another run going the other direction so it's like a basket weave.