It's all done with zip ties. Nothing attached to the coroplast, the cubes are all zipped to the frame and to each other. Only the front two center cubes swing open and are closed with a binder clip when they need to be closed.
Great cage Erin! I am sure the rescue pigs are loving it. I know you have an overabundance of piggers right now so I understand why there are 4 pigs in each cage. I wish I lived closer to you so I could come visit all those piggies and help you out with them.