The interior is hollowed further, removing enough material to create a convincing hollow without removing the structural integrity of the piece itself. There must be enough wood along the 'walls' of the hollow for the deadwood not to break or fall away over time, however, the openings to the hollow can be carved so that they are very thin and delicate, as shown above.
At this point I also started to carefully burn away the 'fluff' and wood-fibres from the stub using a small gas-torch.