Maybe two of those bad boys! 
(one for each hand?) And I always clear the table of any "last build" remnants, give it a good brushing off, put all of the paint jars and tins back in their places and then start at step one most of the time. I fill up my paint thinner and H2O bottles and put away any stray tools. I keep a pretty good feel for when my CO2 tanks might be running low, and will swap them for full bottles if needed before a new build begins. (nothing like running out of "air" when you press the trigger...) Sometimes, I will also place a new calendar page down on the work table top to give me a nice clean surface. I use old aircraft calendars' pages that I tape down to the table. They provide a nice white surface, along with a handy grid feature. And then, after all that, I'm over it...all set to go and pooped out and tired of it all!
No, really, usually I begin, of course! https://www.youtube.com/watch?v=cCYGyg1H56s
