You can always sell anything and you’ll find someone to buy it. There are no legal restrictions of any kind on anything you make with or for Blender. (Other than the GPL license, when it applies, as copiously detailed on the web-site.)
But, you might actually accomplish more by developing the corridor and then publishing the blend-file openly along with a tutorial … or place it with an existing and well-established tutorials site. (Some of them sell tutorials and will pay you a royalty.) In this way you establish your knowledge and expertise.
Then, simply make it known how people can contact you privately and that you are offering your services for hire. Soon, people will begin contacting you because it’s less expensive for them to have you do it (and they’re confident of better results) than to try to do it themselves. Establish that you are a professional who delivers high-quality work on-time and as contracted. As you begin to build your collection of satisfied customers, ask them if you can use them as a professional reference.