My girls outside have chubes, and a huge fiddlestix and their enclosure is really big so when we get big cardboard boxes they go in there for them to play with, they also get empty pizza boxes upside down, really big bed of pro-fleece during winter to help keep the heat their bed. they dont have it in summer as they would get too hot.
My inside piggies who have smaller cages have chubes, i make empty 9" pizza boxes into tunnels just open them up upside down and place open end to the floor and they love running through them, willow balls, various beds.
In the outside run they have little foot stools to sit under, although lola always tips them up so when it rains they get full of water.. not that pigs compain they all like drinking out of them! lol i have the inside chube from a carpet which is long in there too, and normally i bring the toys from the girls enclosure out too the big fiddlestix and tubes etc..