The base was a cheap Ikea hanger. (It belonged to the Antonius shelving system, but Ikea doesn´t produce the hanger anymore...) You'll also need solid wood balls, a drill, contact glue and spray paint. Simple and easy, but be careful when you are drilling the holes to these wood balls and use primer first when you paint!
As mentioned, the IKEA Antonius rack is not currently available, but a similar product, the 6-Hook Over Door Rack, is available at the Container Store.
Find the full instructions at Time of the Aquarius: DIY Coat Hanger.
(Images: Time of the Aquarius)