You'll need:
12 toilet paper roll tubes
hot glue
red & green paints
For half of the tubes paint the inside red & the outside green. Reverse for the other half.
Cut the tubes into strips about 1/2 inch wide & glue 5 together to make a star, keeping the ones that are red on the outside together & the ones that are green on the outside together.
Use one of the colors to be the "big ring" and one to be the "small ring". The small ring uses 5 stars & the big ring uses 7 stars.
Glue the small ring on top of the big ring. Also, clear nylon thread can be used for reinforcement.
Take a piece of ribbon or sting & hand on your door.