Hi Themage, some appartments have a balcony of some sort with large glass door preceeded by a mesh door, if your apartment doesn't have one, a medium-large window will do. When you do your construction and painting work just use one of those small (or medium) sized mobile electric fans. Just place the fan so that it "blows" the fumes TOWARDS the windows (and thus outside). For the environmentalist, you might consider purchasing a fume filter to place at the window so to filter out the fumes.
You can also find a single room (with a window) that will be ONLY used for building models. When painting/construction, work near the window, close your door and use a respirator (NOT face/dust mask) that is able to filter out fumes.
Hope this helps!