How many modders even have business licenses? How many report their modding incomes to the IRS? If it's over $500/yr, it has to be reported, quarterly no less, since it's a business.

I know there are a few legitimate companies that legally make and sell mods, but there are scores of others who are tinkerers that sell them on the side. These are the guys who have no recourse and no room to complain for when a manufacturer starts making their same exact mods(only better) and selling them.

Nevermind the fact that the manufacturer has the option to do the due diligence and get that mod licensed and patented just to shut those modders out. To them, it's nothing. They've got the in-house/on-retainer lawyers already on the payroll. Easy peasy, competition over.

The way to do it is like some of the shooter rods that are out there. Make them general enough artistically that while it can be stylistically associated with a particular game, it can't be inferred that the design came directly from the game. Think "accents" not "duplication" and you should be safe.