Partly scratchbuilt and kitbash. I do a lot of kitbashing. Alot of the models in the gallery are results of kitbashing with moderate scratchbuilding. If the parts fit the bill then little scratchbuilding is needed. I like to use what is available in my scrap box.
If you saw the photo of the beginning stage on the build-up link then you'll see exactly what was used to complete the model.