Green Stuff doesn\'t dry. It cures. Once you mix it up there\'s no real way to stop the curing process. You can probably slow it down or even stop it, if you can freeze it, but the time it takes to freeze then thaw, will be most of the cure time anyway, I\'d imagine, so you\'d do it once and maybe have a very short time to work before it cured after it thawed.
So, work smaller, is the suggestion. Only mix up tiny amounts of GS at a time and only sculpt portions and areas and things you can finish in the hour or so of working time you\'ll have. Most larger scupltures are done in countless layers and sections.