TN Visa and Student Internship Question

I'm a third year graphic design student, and for our second semester of our final year (which is this year for me) we do an internship. I applied for an internship in California, I don't know whether or not I've received the position, however, I want to know it would be at all possible to apply for a TN visa in order to do it, or whether or not I should waste my time with it at all. I can't apply for a J-1 visa, as the company I've applied for is not a sponsored company for the program.

TN cannot be used for internships, as TN rules require you to be a fully paid -- albeit temporary --employee or contractor.

J1 is the only status that allows internships. If you had studied in US on f1, you could intern on that status.as part of your study program.

What if the internship is only 3 months long and unpaid? Do I have any other options that will get me across the border? I mean, I fully intend on returning to Canada after I'd be done.

That what internships usually are -- unpaid and temporary.
It's the fact that it is unpaid that makes it TN-ineligible. A PAID internship (and not just expenses), would work, and only if it is a for a TN-eligible category (GD would work).

TN is for JOBS. Get them to pay you fairly and you can get TN. Otherwise you will have to do your internship in Canada, like the rest of your classmates.