You cannot copyright a product. copyrights only cover specific arrangements, such as artwork or words or code. In order for something to be considered art, it cannot be functional.
Patents cover ideas and products. You are entirely allowed to build anything, whether patented or not. The issue comes in when you wish to use it, as using a patented item is illegal. Now, if you improve upon a patent a sufficient amount, you are no longer infringing upon that patent, as it is no longer the same design, but a new design of your making. If you improve upon it in a "meaningful way", you may now patent (and sell/use) what you built and are no longer limited by the initial patent.
Hit the nail on the head (copyrighted?:laughing