What should I do if I make a product that someone else has applied for a patent for?

If it is for your own use and not for commercial use, it will be fine. If it is used for commercial purposes, please find an authoritative and experienced patent attorney, find out the public information before the patent application date, and ask the patent attorney to declare the patent invalid to the State Intellectual Property Office. The agency fee is expensive, so I suggest you think twice before committing. If you are just a small workshop, you will be fine if you can ensure that you are not discovered by the patentee.