Every time I go to a gas station or somewhere that sells cheepo products near the cash register, such as those lighters shaped like a gun, I think to myself how simple these things are, and how they basically just take existing ideas and just make small changes to it's appearance. I am interested in knowing more about how these product ideas are conceived, designed, produced, and marketed.

Let's use the gun lighter as an example again. I wouldn't necessarily call these "inventions", because they are using existing products (the lighter), but with a new "case" over the lighter (the gun). I'm not sure if I'm right to think this way, but I look at a product like the gun lighter a lot differently than a new invention of, say, a robot butler. A robot butler would need an incredible amount of time and effort to even get to the point it can be sold. Prototypes, testing, market research, etc. It seems to me that something cheap like the gun lighter will sell no matter what if sold in the right places (gas stations, party stores, flea markets, ebay, tourist shops, etc) because it's so cheap. If it costs less than $5 and it's near the cash register, it's going to sell. So, I'm not sure that a product like the gun lighter requires as much market research and such compared to a real invention like a robot butler.

Another example is a keychain. Let's say I saw a keychain with the phrase "don't worry, be happy" on it, and I wanted to make an exact copy of this but with a different saying on it. This seems so simple... just come up with your new picture, design, logo, or saying, and get a copy of the keychain you saw, and then what... send it to a chinese manufacturer and ask them if they can make it and for how much? How do patent laws apply to things like this?

Hopefully you get what I am trying to say here. I am not looking to invent something new, but to make different versions of existing products.