Step 1: Supplies
-Toilet paper or paper towel tubes
-glue or tape( I would recommend using something your pet won't nibble at, I am guessing glues can be potentially poisonous to smaller pets.)
-pen or pencil
Step 2: Create
2)Cut your pieces out.
3)Fold your boxes and other pieces.
4)Put it all together
For more vertical slopes in the tubes I would recommend cutting little slits or notches for your pet to grab onto. I would also put more than one way out....you never know. Again I would advise against using some kind of glue that would be potentially dangerous to your pet.