Please read this entire response. Hey, my name is Shane, I have made a few small circuits in my lifetime but nothing compared to the scale that you are performing at! You are amazing. I live in a city with the largest engineering university in the state of Nevada. It is called U.N.R. Anyway I have come across some people who have built and sold computers before. My brother's friend works on computers for fun and for a living, he makes a lot of money. I have learned many things from many people about the fascinating world of electronics. Though you have obviously learned much more than I have. So back onto the original topic. You have to be aware that there are laws in all 50 states of the United States that strictly prohibit the unlicensed sales of electronic devices capable of harming one-self or others, such as computers. Another thing to worry about is the possibility of a company patenting their electrical components, the businesses that have the money to do these sorts of things are usually well organized, and very powerful. Most likely you will come across a lot of electronic components that belong to Microsoft or Apple. If you plan to mass produce these custom computers, if they contain any components with a patent pending or copyright logo on the name, look up the company name and look for an email address or phone number. If they pick up, you have to ask them if they're okay with your mass production of your products. Another thing to worry about, maybe the second most dangerous thing, is lead, mercury, and other hazardous material that could cause injury, birth defects, insanity, loss of brain cells, mental retardation, and finally death. The more exposure given to hazardous materials, the more serious the consequences can be. The mass production of products you will need a license for only if you are making hundreds of them and/or selling them to other companies. The problem with the use of hazardous material is that selling even a single computer containing very high contents of soft, low quality lead, or any practically any amount of mercury at all, you will definitely need a license for. Lead I wouldn't worry too much about because lead is used in almost all solder, but just to be safe try to use lead-free solder. Also there is one last important thing I have to tell you. Before you make the computer, ask the customer what they would like and what their budget is. Tell them the amount of time it will take to build and that you will use whatever way they feel is comfortable for a way to communicate and get the customer up to date with how you are doing. It is the most professional way to do it in my opinion. Also, just go on Facebook and tell everybody you know to forward your computer sales ad. Make a public ad, as well as your profile itself public, so that anyone can see your custom computer sales. List your email, your average price, and the time it takes to finish your product on your Facebook page. I hope this helped.