Start by making four slits in one end of the toilet roll, as shown.
Fold the pieces in on each other and glue into position.
Punch holes all around the base of the other end.
Then you have two options
1) With markers or colored chalk decorate the toilet tube with squiggles and attach your googly eyes.
2) Paint the toilet tubes with nice bright fun colors and leave aside to dry. When dry decorate with some white chalk and your googly eyes.
Finally loop some lengths of wool into the holes all around the base for the wibbly wobbly tentacles.
If you punch a hole in the top and attach a piece of string you can carry your little octopus friend around and make him dance and wiggle.