I am not a lawyer, but I am a US patent agent, so I have a reasonable understanding of intellectual property (IP) law, especially in the USA. But that being said, this is not legal advice…
There are several types of IP from a legal point-of-view. Trade secrets are just what they sound like. For something to be a trade secret, the company/person needs to take reasonable care to keep the thing from becoming public. Think about the formula for Coca-Cola as an example of a trade secret. Once a trade secret is made public, there is no more protection. I don’t think that trade secrets are coming into play in this discussion.
Trademarks cover symbols that identify a maker of a product. It can be a logo, a word, a phrase, etc. “Swapmod” would likely be covered by trademark law, whether or not it is officially registered as such, as it is being used to identify the source of the product. Even if someone makes an exact copy of another product, there is no trademark infringement as long as they don’t use the same brand-name or logo, or something similar enough to cause confusion.
Copyrights cover an expression of an idea, such as the words in a book or the content of an stl file. Copyrights are accrued when something is created without any extra registration, although there are official processes to register a copyright. Copyright is the only area of IP law to have a “fair use” doctrine, meaning that there are some specific exceptions which allow a copyright to be ignored, such as making a backup of something. But a copyright can’t cover the underlying concept. For example you can copyright a photo of a lighthouse, but that doesn’t preclude someone else from taking another photo of the same lighthouse, from the same angle, under similar lighting conditions, and copyrighting that photo themselves.
Design protection (design patents in the USA, design registration in most other places) covers the ornamental design of something. It must be applied for to obtain. Someone else can make another product that does exactly the same thing as long as it doesn’t look the same. How much different it needs to look is always a point of contention, but generally, things need to look almost identical to the actual design element that is protected to infringe, but this is a long involved topic.
Utility Patents cover the way that something is built or the way that something functions. The protection offered depends on exactly what is claimed in the patent, which can be very broad in some cases, but may be very narrow in other cases. Utility Patents are fairly expensive to obtain (thousands of dollars) and take quite a long time to obtain (2-3 years is typical), but offer good protection from competitors in many cases. There is NO fair use doctrine for patents, although the realities of the costs of enforcing patent rights means that you are unlikely to get in major trouble if you infringe a patent for your own personal non-commercial use - BUT you could.
From a legal POV, if a new product/company is not infringing on a competitors IP as defined above, then they are probably not in legal jeopardy in bringing their competitive product to market. This is how capitalistic markets work and how new technology and lower prices emerge. From what I have seen in this thread, while @Theodor may have taken the same idea described by others for use in his product, whether he is in legal jeopardy or not depends mostly on whether patents have been applied for by others. And he will probably not find out about that until at least a patent application is published which is about 18 months after it is filed.
I will leave the moral implications to others, but people copy other people’s ideas all the time in business. Intellectual property laws are set up to define boundaries of what types of copying are deemed legal and proper competition, and what types of copying are not.
