I am new at Arduino and don't know much about the boards.
Then a 3D printer is an awfully ambitious project. I'd grab an UNO and do a little bit of learning before getting too far in. Learn how to run 1 stepper. Learn how to write some of the code.
This is like saying, "I really don't know how to swim yet, but I'm going to try to swim across the English Channel. Can you guys tell me what sort of swimsuit to buy" And this is for a final project so it sounds like you have a lot riding on it.
You also need to get a feel for how big the code is going to be. That's a very important spec. You may be able to drive the steppers with an UNO and a could of stepper driver chips, but if the code doesn't fit then you're toast.