[vtkusers] Is there a way to build a volume like this?

[Michnay Balázs]

Dear VTK Users,
I've seen many examples on how to build a volume from image
files stored on the HDD (using SetFilePrefix and
SetFilePattern of the reader), but what should I do if my
images are created run-time?
Writing the images to disk and then reading them back is
certainly unnecessary, there must be a way to add them to a
volume immediately they're creted.
The images have different extent size. Is is still possible?
(I hope so...)
Thanks for your help,
  MB