What does "semi-commercial" mean? Either you're making money off of it or you don't; if you do, you need to contact Disney's licensing department and be prepared to fork over a ton of cash for the priviledge (Even if you plan on donating everything you make off of this, this is something that Disney's lawyers will have to get involved in).
If you make something without any commercial aspect whatsoever, then it is fan art. But being fan art isn't a perfect shield: Disney's lawyers can and will shut you down if whatever it is you're doing threatens to damage the brand.