Section 18 of the ACL does not of itself prevent a competitor from copying the product of a rival.
A manufacturer does not contravene s 18 of the ACL merely by copying an existing product, provided that it does not represent that its product is the original.
No representation of this kind will be made provided the manufacturer has adopted an adequate branding strategy to identify the product as its own.
Thus, the mere copying of another’s product will not of itself mislead consumers, provided that the imitation product is sufficiently differentiated from the original through pricing, branding and branding positioning, promotional strategies and retail supply:
Parkdale Custom Built Furniture Pty Ltd v Puxu Pty Ltd (1981) 149 CLR191;
Dr Martens Australia Pty Ltd v Rivers (Aust) Pty Ltd  ATPR ¶41-734;
Moroccanoil Israel Ltd v Aldi Foods Pty Ltd  FCA 823.
In fact there are businesses out there to help you get it right (and this is not an endorsement of that business, it just serves as example, I have never had contact with them nor examined their products in any way).