Snake Playpen?

[Lolo76]

I was just wondering, has anybody here made a "playpen" for their snakes to safely roam? I used to keep guinea pigs (3 at one time), and set up a dog playpen for their free time... I'd stretch it out as big as possible in the bedroom, and they'd go NUTS popcorning and running around together.

I don't think one of those would work for snakes, since they have holes big enough to slip through - and most are low enough for them to climb. But I do feel bad never letting my snakes wander freely (too many places to hide/escape in my current apt), so thought I'd see if anyone has ideas. If not a playpen, how do you all let them get safe floor time?