I fell in love with Pixar long before they made their first movie. In the early to mid 1980's Pixar was owned by Lucasfilm and created a great piece of Mac software called Renderman. Ultimately Pixar was bought by Steve Jobs then sold to Disney but the software continued to shine regardless of who owned it. Renderman software was used in movies like Titanic, Star Wars, The Lord of the Rings and other Hollywood blockbusters.
By today's standards the early versions of Renderman were a bit crude but it had a lot of power and the results were spectacular, even by today's standards. It was used to make the the Genesis Effect in the 1982 movie Star Trek II.
Although the software runs on most OS's today back then Renderman ran on a Mac I would have bought a copy but it would have been a very expensive toy. Today I just got a notice that the non-Commercial version is now free. Looks like Pixar just made a lot of budding animation directors very happy.
Renderman isn't a simple application. You will need to have a way to create your model files using an application like Autodesk's Maya, Katana or other 3D CAD or meshing application. If you don't already have Maya, you can try a free trial. Maybe you can create your own movie masterpiece like the one below.
So, if you want to try your hand at the next great animated movie go to the Pixar web site and download your copy. If it sounds like too much work, then just head over to YouTube or Vimeo and watch some of the great Pixar Short films like Geri's Game, Day & Night, Paperman & my personal favorite Presto. All of them were rendered using Renderman, a professional quality tool that's now free.