clement Yes there is a way to do that currently. Admittedly it is a bit of a hassle right now. That is what James was referring to was to make that easier to use. Having said that you can play with it now. The idea is that you can filter what you want at build time. So in your example above where you want to just transfer material properties you would add some arguments to the build command like so:
z.build( solver=False, bones=False, tissues=False, attachments=False,
materials=True, fibers=False, embedder=False, cloth=False,
fields=False, lineOfActions=False, rivetToBone=False)
Looking at this now it could be useful for a slight refactor of using a type filter where you just give it a list of node types you want to build.
Hope this helps