in complex profiles, you can even have one fill type with varying material finishes - just add edit points on the fill edge at the location where you want the material to change and then call up the pet pallet for each segment (left-click on specific segment) and use the last button shown on top row to assign a specific material. This has worked well for me on occassion, although it is limited to horizontal layering of materials.
Another technique i've used is to assemble a facade design on a hidden layer from thin elements (walls, slabs etc. with varying materials assigned to them) and use them as as solid operators (with "inherit attributes of operator" selected). This gives more flexibility in the composition of the materials and it relatively easy to edit.
