The small playpen and a few of many toys.
The big playpen where the toys also get replaced from time to time.
Or combined :)
The skylight with blinds, air conditioning (which ventilates as a default), chandelier, clock and sink to fill water bottles provide additional convenience in the playing area. The sliding door provides the ferrets access to the outside playpen.
The whole garden is ferret proof and can be used as a playpen. When the french doors are not open in summer, they can experience the all climate and scent changes.
When the french doors are open, we use the midwest playpen. It is flexibel to whatever size and shape I need. The photo below gives a good overview from 2014. The other dubble photos are in our current garden, where I always make weirder shapes.
Whenever I go away with some ferrets, I have several canvas playpens. Very easy and light weight to use! This one is 160cm in diameter.