Well I gotta say, "Never a dull moment!" Not being a builder, only a painter it may not be my place to speak here. Ethically speaking, to copy another design and call it your own is wrong. Realistically speaking, its done daily on thousands of items, but that does not make it right. As Matt and many others on here can attest, Lure innovations, design and testing can take weeks or even months of trial and error to deliver a working model. Once you comprehend the basic fundamentals of the lure you want, you should be able to design, build and produce your own lure. Even improve upon the original design of the one that gave you the idea. That's what most inventions or ideas stem from, Seeing something in action and developing an idea to improve upon the original or designing something new due to necessity of the moment. If you can copy and build a lure from scratch, you can probably design and build something better than what you copied in the first place.
All that said, and I didn't even have to go down to the schoolyard mentality level to say it, but as I stated in the beginning..."Never a dull moment!"