This is such a faboo project! I really want to make one but it'll have to be shorter as I have a kitty who will see the pom pom curtain as a personal cat toy.
Love the edited photo you added of the kitty attacking the curtain! I'm glad I wasn't drinking when I saw that! lol!
I found some in Kmart in the homeware section, near the candles. My local store has coloured and clear ones. They usually have the small ones but I have seen some of the larger marbles in the past. Good luck!