This is probably the most simple yet effective cardboard invention ever. It is mainly for the sqeamish and easily scared people.

Step 1: Part 1:The Main Body.

No.1, Carefully peel the tabs of a large cereal box apart to reveal the net.
No.2, Draw around the end of a circular tube onto the box.
No.3, Cut the circle out to leave a hole the tube will fit in perfectly.

Step 2: Part 2:Main Body Continued.

No.1, Fold the net in the opposite direction to how they were before.
No.2, Sellotape the tabs tightly.
No.3, Cut the highlighted piece off.

Step 3: Part 3: Door.

Once you have removed the front, sellotape it on to the small tab that is left behind.

Step 4: Part 4: the Neck.

No.1, Very carefully, pierce a hole about 3-4 inches up the tube.
No.2, Thread some string through the hole.
No.3, Make sure that the string comes through the long end of the tube.
No.4, Tie a pencil onto the end of the string to stop it falling out.