Comment Like photo printers (Score 1, Interesting) 400
Remember how photo printers put photo shops out of business? Not exactly. If you want prints, it's usually cheaper to go to the local drug store or box store and print them out there than it is to buy the special paper and ink yourself. It will likely be the same with 3-D printing. If you don't do it all the time (and most people won't), it will be cheaper to print your designs at a local shop. They'll have the large high-quality industrial printer that you can't afford, along with a wider choice of materials than you could stock.
What it will do is cut into the profit margins for mass-produced items. They will have to compete with the price of printing out your own design, not just what other companies are charging. That will eat into the profits of retailers.