Pixar is giving away Renderman, a $500 piece of software, free at its site here.
That's the software that earned the Pixar team an Academy Award of Merit in 2001.
You may, or course, need to upgrade your computer a bit if you want to be able to process your creations quickly. Rendering a lengthy, detailed animation isn’t the kind of task you’d want to leave in the hands of a Core i3 laptop. You could, however, and if you’re not paying for the software and just want to fool around, it would probably work just fine. Slow, but fine.
You need to go to the Pixar site and register to receive the free, non-commercial download. Have fun!