This was an idea caught on Pinterest. The usual ball bought in a supermarket, hanging on a string inside a cage made of sticks. It took me some time to realize that all the joints were not tied with knot in fact. It was connected with a hot melt glue gun! However, the knots are great there anyway, as the glue works the best on rough surface, better than on smooth bark.
I also used a crooked birch branch to hang the feeder so that our balcony stays clean even with the bird visitors coming. At first, the birds were frightened that the cage moves when they fly in and break just before it - it began spinning. But after some time, they got the hang of it and a flock of tits kept coming regularly, having fun on the feeder.