Creation of raw files (or better yet, the raw assets files)

If I create a 3d "model" - basically, a series of planes (or short cubes) which have textures on them, how do I get this in the .raw file? Or better yet, how do I get this into the .raw asset format needed for the 3d volume rendering app to work?

I have my own scans and would like to insert this as a model (instead of the head in your example).

What is the process for this? Thanks much!