OK, I wouldn't risk it since he is a HUGE chewer. It is definitely best to be extra cautious. I have made things for Eros in the past. However, some of her absolute favorite hideouts are boxes and she treasures them tremendously as if they were her miniature palace, lol.
If you do decide to try the same DIY project again using only water and toilet paper, I agree that dipping the paper in the water just enough to make it damp prior to attaching it to the mold probably will work better. You could also apply the layers in stages and let it dry overnight prior to applying the next few layers. That may also help. I did that when I made ornate homemade paper masks in high school art class, and the key was letting each stage dry thoroughly prior to continuing. If you try again, I will be wishing you the very best on your project and would absolutely love to see Kylo's finished hideout. I always love DIY projects, lol.