As Patent Attorneys we are often asked the question: Do I need a patent to make my product? The answer to the question is no, you do not need a patent to make something. A patent provides the negative right to prevent others from making, using, selling, or offering to sell the invention. A patent does not provide any right to you to make, use, sell, or offer to sell an invention.
For example, a question often faced by our patent attorneys is the following: If Company A is making product X, can I get a patent on an improvement to product X? The answer to this question is it depends on if the improvement is patentable or not. In the U.S. the questions are is the improvement novel? and is the improvement nonobvious? (in Europe this second question is did the improvement require an inventive step?
The next question typically asked is if I get a patent can I make the product? The answer to this question depends on if Company A has a patent or not. If they do, you cannot make, use, sell, or offer to sell whatever their patent claims without running the risk of infringing that patent. It would be a good idea for you to have a patent attorney analyze your product and any patent allegedly covering the product. It is possible to get a patent on an improvement, but not be able to make the base device because another company owns one or more patents on the device.