If you want to manipulate your model after you scan there are multiple ways that you can
If you have some 3D modelling skills the best option is to use your scan as a base for modelling in a traditional modelling software. Both 4D Cinema and Blender are taught in the Digital Space if you want to learn how to 3D Model
Blender is an open source, free software which allows for traditional solid modelling as well as sculpting. On top of the training available in the Digitial Space there are plenty of good tutorials available online and through Lynda.com
Sometimes this type of scan manipulation will produce files which may have holes or degenerate geometry which will not 3D Print correctly. To check and repair files you may want to consider using Netfabb (which is free for students).
The software currently only runs on Windows. There is an older, unsupported, version of Netfabb Basic for Mac which you may be able to find online (alternatively you can use on one of the computers in the 3D Workshop).
The following video explains how to fix files: