"As I mentioned, I was a carpenter for a time"

Jack Vance's quote suggests that he had a career as a carpenter at some time in his life. This might mean that he was an expert carpenter, or that he just worked as a carpenter for a time period. It is possible that he was a carpenter for a few years, and even simply a few months. It is also possible that he was a carpenter as a side job while he pursued other interests. Whatever the case, it is clear that Jack Vance had some experience as a carpenter. This might have been a formative experience for him, as it might have taught him important abilities and lessons that he could apply to other locations of his life. It is likewise possible that he merely delighted in the work and discovered it to be a satisfying experience. Whatever the case, it is clear that Jack Vance had some experience as a carpenter.