programs for 3D representation of biological objects

[laura Vergani]

Can anyone tell me if there is free software for representing the chromatin
in  situ? In fact I'm working on the chromatin structure and I'm interested
in investigating the chromatin organization and distribution inside the
nucleus by fluoresence microscopy. To this end I'm using the optical
sectionning technique and I would like to represent the 3D nuclear
chromatin structure as final step of my work. 
Thanks Laura