I am a member of the Nerf Internet Community (I am a Nerf hobbyist, one of many), and I have a couple questions about reproducing a toy made in 1995.
I think the patent has expired, but I can't be certain because I haven't been able to find a copy of it.
The blaster in question is the Nerf Action Crossbow made by Kenner.
Doesn't have the box have some of the patents listed that the toy is protected by? Go to the USPTO and put in the numbers.
But, I don't think there will be "a" patent, but many. Some not disclosed. Some improvements like those you want to make may have been filed later. That's why patent attorneys get the big bucks. They do good searches of potentially infringing issues. Even then, they never make a promise. There can always be a greater search in more depth. All it takes is more money.
I want to cast copies of the shells (exterior component) out of resin, rather than the injection-molded plastic they were originally made in.
(I would also make a few other changes to the inside of the shell.)
My first question is: Am I allowed to make these variants?
Second: Am I allowed to sell these variants? (On a small scale, I could never afford to make these on the same scale that they were originally manufactured on.)
Third: Should I label it as "Derived from Kenner Nerf Crossbow"? Is there a different way I should give credit to the original design?
I don't want to get into trouble with Hasbro's attack lawyers, so please help me out.
This is where I suspect the real issue(s) will lie. Now, just because the toy is old does not mean those rapacious attack lawyers have not been getting more patents that covers your changes. It is right to worry about patents. I think it the real problem will be other intellectual property issues. The fact you want to say it is derived from a specific item can give rise to confusion on the part of others. Confusion can be bad to those who do not want to poke the bear of rapacious attack lawyers. Confusion is where they make their real money. Don't get me wrong, it is not the fact you want to give homage to Kenner for their Nerf Crossbow (Note how I capitalized it. Think of why.), but the fact you think it is related in some way that will cause a problem. That you want to cast "copies" of the shells makes me think of a time long ago when I was walking a dog and passed by a fence and saw an unattended trampoline in the front yard of a person's concrete driveway. Even without getting into the tall weeds (As quincy might.), um...that scares me a bit. I don't know how good it would be on you for one side of the balance. On the other side, I see very bad things. Very bad things. Things rapacious attack lawyers who don't have their day otherwise filled love to see. I suspect they will giggle a bit as they have their secretary cut and paste the basic cease and desist letter with your information added. "Look how cute, he thinks resin is different from an injection-molded plastic look."
Unlike Silverplum, I am not appalled with the "attack lawyer" quip. I added rapacious, for fun and truth. Let's just say there is not a lot of pro bono work in enforcing intellectual property. While the basic theory of patents should allow you to use the invention as you plan. (If the patent is expired and others do not cover your thing.) The Constitution's point on giving patent rights is for others to benefit. (See the Federalist papers for the discussion.) The problem is that those who invent things have the money to get "access" to legislators who make other rules. While not certain, I suspect those "other rules" are not designed to promote society, but to have people profit. I love profit. I love that those who invent get profit. Defining how something looks or feels is "property" is more problematic. I don't know the solution, but I KNOW current IP is stupid and wrong. I accept those who profit from the nonsense disagree.
The bottom line is that if they care, they will litigate it. If they litigate it, you will lose or pay more than you made to defend it. As to if you violate current law with your plan, I have no idea. (More trade law [trademark/trade dress] and such than patent. Even though patent may still be in play.) Even with the ability to pay for a defense, the result is still uncertain. That is why the rapacious Hasbro attack lawyers are not merely protecting the intellectual and creative rights of intellectual and creative people. They are stifling the intellectual and creative person writing here (The OP) in order to profit their boss while knowing that even if the OP is correct, he cannot defend against the onslaught.
The OP does not want to steal from anyone. He is a fan of the weirdest kind who wants to write a fan fiction in reality with improvements and have others enjoy his invention. I would advise he does not. Especially if he wants to profit or pay for his invention even slightly. I'm not sure he should be able to profit. I am quite sure I would not insult him for talking about rapacious Hasbro attack lawyers. IP law is wrong. Finding the correct line is hard. Rapacious Hasbro attack lawyers will always push it further than the theory of the law allows.