free program to make primitive cells and supercells

I am looking for an opensource program that can create primitive cells and supercells for all types of crystal structures. I would like something similar to Crystal Maker or Materials Studio (it doesn't need to do all of the other things that these two programs can do). If it was a Java program that would be even better.

Sorry for the delay...

What exactly do you need? I'm working on an open source molecular editor/builder that displays crystal cells. Do you want to take an existing crystal file (e.g., CIF) and make a super cell?

If you can explain what you want, it's probably easy enough to handle with Avogadro. It's nice clean C++.