A thank you letter can be a good time to write what you forgot to say in the interview. Whether you were nervous or ran out of time, take this time to say what you forgot. Just keep it short and to the point. Also, the whole point of the interview was to sell yourself. If you are finding that you have to restate your qualifications in the thank you letter, then you did the interview process backwards. It’s okay to list some skills you possess, but do not list things like your education or certifications.