Ideas for extra large garden run?

We’ve got our two fuzzies in a large outdoor enclosure, which provides them with tons of space and enrichment opportunities. However they love the garden, and all the smells and things to snuggle and dig in. When they were young, it was very easy to let them potter around and explore, but now they’re older, they’re very fast and it’s a bit stressful chasing them around to make sure they don’t escape.

So I wanted to see whether I can build/buy something.
Perhaps modular, made of panels, so that I can change the size, shape and location as desired. But whatever it is, it would need to be very big. Not sure there is any mesh on the market that ferrets can’t climb, as even the ones with primarily vertical bars have the odd horizontal bar in there to maintain structural integrity.

Any ideas.

I used to have a handmade one, 8ft by 8ft, a few foot high. It was wooden framed with wooden supports and meshed all round, the top was open but for two planks of wood around the edges of the top which stopped them climbing up and out and also meant that I could sit in with them. It had a hunch attached for some shade if they needed it.

Hmm, that’s a good idea having planks at the top to form an overhang rather than fully fenced at the top. I’ll look into that. Ta