I have this one - it's great! I started out with a home made one (tutorial on this forum a few years ago) made out of sheets of correx/coroplast held together with bulldog clips - but wasn't completely escape-proof and needed constant vigilance! And to be honest the sheets of correx cost me about the same as this playpen. There are other, maybe cheaper, options as well - I'm sure others will post alternatives. This one can either be left up in place or taken apart like a jigsaw. But you have to be a bit careful with the little side tabs not to break them off - if taking it apart and putting it up a lot. I left mine up for quite a long time but now just get it out when needed.
https://www.zooplus.co.uk/shop/small...g/73299/453205