Thought of a better example - that more people on here can relate to. I will try to speak vaguely so I don't get anyone in trouble

, but the board regulars will know what I am talking about and can read between the lines, and the others can do some research.
Let's look at "above-panel switchable 4/8-way joysticks". And I am thinking of three different products from two different vendors.
All of these are based on an existing product and modified by the vendor. I suspect either the vendor got permission from the original manufacturer to modify and sell their product, or the original manufacturer doesn't care as they are still selling one joystick for each modified joystick that the vendor sells.
Now -
Lets say that the vendor develops a custom handle (which one of them has), different microswitches (which one of them has), different return mechanism (which both of them have). At this point, all that really remains of the basic stick is the base and possibly the actuator. Can the vendor now (legally?) have these parts manufactured for a lower cost by a third party company in China? (If not, how much do they have to change the design before they can have it produced by a different company?)
As a different example, let's suppose one of these sticks is based on the Happ Perfect 360 joystick (none of the current ones actually are, btw). I can see four scenarios:
The vendor markets the sticks as "based on the Happ P360 design" and the stick performs well. Legal or not, Happ is unlikely to complain, b/c they may still be selling the stick to the vendor, people that may want the stick but want a lower cost option may buy the Happ instead. And if they take legal action to shut down sales by the vendor, he might partner with a different supplier, costing them sales to both referral customers and the vendor.
The vendor markets the sticks as "my own design" and the stick performs well. Legal or not, Happ may complain or not, for reasons above. Hard to say. . .
The vendor markets the sticks as "my own design" and the stick performs poorly. Happ likely would not complain until some user or website figures out that the stick is in fact based on the P360 and the negative publicity starts affecting them.
The vendor markets the sticks as "based on the Happ 360" and the stick performs poorly. You would probably see legal action as Happ wants to preserve the reputation of the P360's.
Just random musings . . .