Liquid Foam claims to expand to 25 times it's liquid volume. You stir the two fluids until it turns a milky color and then you have only a few seconds to pour it into the crewman figure before it foams up. The instructions suggest you play around a bit before using it for real. I used some little creamer cups and a stirrer from McDonald's coffee as my mixing tools. I took a scrap of carboard to make a mixing tray. This worked fairly well. The tray gave me enough control to pour it down the crewman's neck hole without spilling.
Here it is foaming out of the pingpong ball that will go on top of the mast: