Actually, GL won't send you to jail for doing Star Wars stuff as long as you don't sell any of it, not even renders. So you can pretty much make all the fan art you like, provided you keep things like Darth Vader getting jiggy with Palpatine out of the reach of kiddies. ;-)

Disney, otoh, is so uptight about what it considers theirs it's a wonder they even have fans, what with all the C&Ds & lawsuits they keep slinging around.