Some products can be protected by both copyright law and designs law.
Copyright protection is automatic, it doesn't require registration and it lasts for the life of the author plus 70 years. By contrast, design protection lasts for only 10 years. But designs law provides more legal certainty than copyright law when it comes to products.
If you register your design for a 3D product, copyright will be extinguished and you will have to rely on your design registration.
If you register your design for a 2D artistic work (such as printed wallpaper), then you can still retain your copyright protection in the artistic work.
If you "industrially apply" your design, then you could lose copyright protection. A design is generally taken to have been industrially applied if it is applied to more than 50 articles (see section 77 of the Copyright Act 1969 and regulation 17 of the Copyright Regulations 1969). The only exception is if the articles can be regarded as "a work of artistic craftsmanship", in which copyright protection will still apply.
The meaning of a "work of artistic workmanship" was the subject of the case of Burge v Swarbrick [2007] HCA 17. Mr. Swarbrick is naval architect who designed a sail boat called the "JS 9000." His legal opponents copied the boat design.
Mr. Swarbrick admitted that the boat design had been industrially applied. He had not registered the design of the boat. So he had to argue that the boat was a "work of artistic craftsmanship" in order to retain copyright protection.
The High Court said that a work could be one of artistic craftsmanship, despite its form being partially dictated by functional considerations. The High Court also said that question of whether the artistic work is a work of artistic craftsmanship "turns on assessing the extent to which the particular work's artistic expression, in its form, is unconstrained by functional considerations." The more you have to rely on utilitarian considerations in making the design, the less scope to encourage substantial artistic effort.
However, the High Court ultimately held that the boat design was not a work of artistic craftsmanship. In designing the plug for the boat, Mr. Swarbrick's primary aim to create a boat that moved fast in the water, and, in seeking to achieve that goal, he was acting more as an engineer rather than an artist.