While I appreciate the time and effort you put into this, I do have some feedback that is not positive.
First, reading your description of the construction of your trackballs leads me to believe that they are fragile. I am not sure if you have ever seen people play trackball games like Shuuz, Golden Tee, or Shuffleshot, but they need to withstand quite a bit of abuse as well as be calibrated to spin pretty fast and still track. I would bet that a couple GT drives would be all it takes to damage or destroy your trackball. There is a reason that trackballs use heavy duty rollers and not just a few pegs to ride on. Also, trackballs typically use rollers with optical wheels because A) you can make very high resolution wheels for both precision and a wide range of speed detection, and B) because optical sensors like IR or laser require texture to sense the movement. The newest lasers are OK with smooth surfaces, but still need some kind of texture to see the movement. You want trackballs to be as smooth as possible so they roll good. As for what kind of ball to use, the larger the ball, the more precision you get, which is important for some games. 3" seems to be the "sweet spot", and when doing anything DIY, juggling balls tend to be the choice most used. And I believe there is a thread here for a ps/2 2" trackball that people have had good luck with that costs like $20 or less.
Second, While I appreciate that you figured out a way to translate an analog voltage to an X axis for spin, it sounds like you still have a lot of bugs to work out there. Optical spinners can be used with a variety of controllers. The reason I point this out is it seems that if you were to market this spinner, it would require your proprietary controller and software. If you are looking to sell hardware based on your designs, people would be turned off with the lack of compatibility with their existing hardware. If you are looking to sell complete units, you will leave out people like you find on this forum because anyone who is into customizing will not want a prefab controller (this is after all a forum about building your own controls, people come here to figure out how to do things themselves). And if your intent is to sell instructions on building your own spinners and trackballs and controllers, you may be asking too much of a general hobbyist, especially since your spinner won't be compatible with anything else out there.
Third, your controller. Again, I appreciate that you did it yourself, that is a great accomplishment, especially considering your challenges with the spinner. But there is already projects that can net you a complete encoder for literally a few dollars. Kade has become well known and with a $6 part, a little soldering, and some software you can have a fully functioning encoder. And analog and optical controls are being worked on or are available with slightly different hardware. Then there is hacking keyboards and game pads, which can even be cheaper. But none of these will work with your spinner, just everyone else's products on the market.
Fourth, it is one thing to build something that is not so pleasing to the eye and somewhat fragile and tricky to get dialed in right because you are the one who is using it and you already have the satisfaction of making it work to override the dissatisfaction of the glitches and other downsides. It is something else entirely to expect anyone to shell out even a quarter to use your designs or products to end up with a sketchy product. There are dozens of free designs on this board for various arcade parts that people can build at home. But I think anyone who is going to pay for a finished product will want quality that exceeds anything they could build from some free plans on the internet.
I hate to be the "negative nancy" here, but I tend to agree with the earlier posts here. 10 years ago your ideas might have been revolutionary and unique, but frankly what you have here is a kludged together DIY control panel that shows some great ingenuity, but nothing truly innovative. If you really want to market anything, spend some serious time reading this forum and others like it to see what people have already done and shared for free, do your market research of the major brands and retailers out there who sell competitive products, and then come up with something you can get patented and manufactured on the cheap that people might be interested in buying. The ones who successfully took their ideas to market and have profitable businesses are the ones who were able to get their designs through the alpha and beta stages, work with manufacturers to come up with ways to build them on the cheap, and spend the capital to produce high enough quantities to where they could make a profit selling them.
It seems your intent overall here is to take what you did with your control panel and come up with a way to make money off it. I just don't see that happening, but that is just my opinion. Most people in this community will come up with stuff like you did just so they can share it and spread it around. I am not saying that you should give away your designs or share anything, that is up to you. I know first hand how difficult it is to put thousands of hours into something and not have a product that can be marketed. And the fact is, most people who end up making money "inventing" something do so after a few hundred inventions (and many many years) that don't go anywhere.