The subroadbed has been spackled to hide screwheads and cracks, as well as building up roads and subtle hills. The spackle has been sanded and painted with the base dirt paint.
The next step is masking off track and anywhere else that shouldn't get covered with the plaster and tempra powder mixture.
Paul and Brandon are using blue painter's tape to make a dam at the edge of the layout to keep plaster/tempra mud from dribbling down the fascia.