If you are considering protecting your product by registered design, be aware that certain products or design features cannot be protected. There is exclusion from registrablity for features dictated solely by the products technical function. An example of this is the serrated blades of a dressmaker’s crimping shears, which create a sawtooth edge on what is cut.
Interface features or products which are compelled to be of a certain exact shape in order to be able to fit into, around or against some other product so that ether or both of the products can perform their proper function. The remaining features of the product may well be registrable but these interface features are not. The law does allow however for protection of features that allow for assembly or connection of mutually interchangeable products within a modular system; such features can now be protected and registered (although would still need to be new and of individual character). This provision tends to soften the blow that interface connections can never be registered.
Under the law before December 2001 it was not possible to have design registration for a spare part. However, it is now possible to have such a registration providing the part is visible during the normal use of the whole product. For example a new design of a radio aerial for a car would be registrable if it was visible but new design for an oil filter for a car would not as it would be hidden during normal use. Normal use means that the visible parts of a wing mirror for example could now be registered as they are visible in the ordinary use of a car. A design registration cannot be used against someone supplying a spare part for the repair of a complex product so as to restore its original appearance, for example the radio aerial. So while registration can be used to stop another manufacturer from using that design if aerial on its make of car it cannot be used to stop someone supplying spare aerials as to restore the appearance of a car made by the owners of the registered design.