Honestly, I don't like the excercise balls for degus. I'm sure there are some degus who don't mind them but I haven't met many that really enjoyed them. Mine all hated the balls and could get out easily. I think degus prefer having more freedom.
I let my degus out in the bathroom. Hikaru has to stay in the bathtub unless she's in a calmer mood because she's crazy, hehe. Ichigo can roam because she's a good girl

. When I take them out I always sit on the floor with them...Ichigo likes to hang out in my hoodie or shirt while Hikaru perches on my shoulder. I put a bunch of fun things in the bathtub like boxes and cardboard tubes. They love playing with towels and if one of them is feeling destructive they can rip up a hay-filled brown paper bag. Sometimes I hide treats and even if I don't they get some anyways since when I call them I give them food to keep them motivated.
Ichigo is tame enough that I can bring her into other parts of the house. She loves to hang out in my hoodie...it's a habit that started fairly recently. She'll hang out in there all day...only occasionally poking her head out for attention. I can even bring her outside because she won't leave the hoodie, haha. Plus she doesn't mind being picked up (though I only do it if I have to). I'm going to start bringing her to stores, I think

. I bet people won't even notice! And this way if someone asks what a degu is I can just show them

. Hikaru sometimes sleeps in my hoodie but only if she's in a calm and cuddly mood (most of the time she's energetic and playful but sometimes she becomes the snuggliest degu ever and will sit in my lap wanting to be pet all day).