So, I had two little dogs over to play and they were running around the part of my backyard that's fenced in and I was filming it when all of a sudden, I realized one of them was on the other side of the fence! One is small enough to fit through the wrought iron portion of the fence. The fenced wall is rectangular and the two parts facing the front yard are wrought iron and are about maybe 100 ft or so long.

So, what I need is an idea of what to line this portion of the fence with when they come over to play. It has to be cheap because I don't have a lot of money and it's such a long area, and it has to be removable because my parents will only allow it to be up when they're over here and will immediately want it to be taken down after wards.

And it's very important that they be contained in the yard because they're rescue dogs and there's nothing to keep them from realizing they're free and running away forever if they get out.