Well, in California, you would probably be classified as some type of Artisan contractor. Probably in the lines of a cabinet maker/carpentry.
Please check with an INDEPENDENT agent who has access to many carriers and is familiar with business insurance. Captive agents (like Farmers, State Farm, Allstate) can only sell for their own company and they don't have access or the knowledge of the various coverages for a specialized risk. This is not difficult to classify and you should be able to get a quote fairly easy.