The details are finished for the underframe. I want to go ahead and paint that first before moving on to the next step. I think it will be easier to paint it now rather than wait until it is installed. The photo below shows the underframe airbrushed with Floquil's "Grimy Black". It has just the off-black color I was looking for. This was the first airbrushing I had ever done, and I am happy with the result (it is more black in real life than it is in the photo).