Masts can be built almost independant of the rest of the model construction. They are fully completed with tops, trucks, half-moons etc. Of course the bowsprit can be considered a mast also.
The masts are normally fixed in position when most of the deck and hull detailing is done. They would just be in the way otherwise.
Yards, gafs, and booms are left off, until after some of the standing rigging such as the stays and shrouds have been applied. The image below shows masts at different stages of construction.
It is at this point that the model is finally starting to resemble a tall ship. The last deck, hull and mast details make their way onto the model, before her rigging can be completed.
I extensively use airbrushing techniques for large and small surfaces and to create a variety of effects. The thin layers of paint created through airbrushing also allow the woodgrain, tiny detail and plank-to-plank edges to remain visible, often adding to the realism of the model. Dry-brushing is sometimes used for simulated rusty or worn-edges effects.