Learn how to write an interior designer cover letter. Get expert tips and downloadable cover letter examples for all levels of experience.With over nine years of experience in interior design, I've developed the skills and knowledge necessary to successfully complete projects both large and small. A cover letter is your chance to communicate what makes you, you. It is additive, though not consistently required, as part of your application package. Junior Interior Designer Cover Letter Example. Dear Hiring Manager, I am reaching out to express my interest in the Junior Interior Designer position at HOK. A good cover letter is typically short (usually three-to-five paragraphs). I am writing to apply for the Interior Designer position at your company.