There is a pop up play pen on Amazon. It’s about 12$ it’s amazing and it comes in huge sizes! One is so big you can sit in it with Him. I have one and it’s amAzing. I lay a blanket on the bottom and toss in toys and let My little Dude go to town lol. He runs all over in it. I do make sure to stay close and not let Him out of sight. I don’t think they can get traction to climb the sides but you never know. play pen

This is the one I have. It’s cheap and works great and folds flat for storage. It’s also easy to clean!