Yes, there has to be a barrier that they cannot squeeze through. I don't like plastic because it does not last. It gets brittle and weed eaters destroy it, though some plastics last longer than others before turning brittle. But watch lawn movers throwing stuff and weed eaters.
I don't know how big an area you are talking about protecting. Youi can look at Lowe's, Home Depot,
Tractor Supply, or maybe a building supply company to see what you options are for fencing and posts. I got a 150' long roll of 5' "No-Dig Kennel" fencing from
Tractor Supply a couple of years ago for a little over $150. My
TSC does not stock it any more but you might be able to get them to order it for you and avoid transportation. That roll is pretty heavy for one person to handle, but I managed by myself.
Your corner posts need to be pretty substantial and well braced, but the intermediate posts don't have to be as sturdy. Watch your gates. Those are often weak points in your security system, especially if you make them big enough to get equipment through.
Good luck with it.
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