if you have a small area to smooth out take a Q-tip and use CA debonder to loosen up the CA, then quickly wipe off the extra CA and again quickly sand the area before the glue re-hardens, its a pain but it works in a pinch, like ken said if you have a area that you know for sure your going to need some sanding or shaping then a tite bond or similar type glue sands much better I use allot of CA in my building also. another way if you are doing a area of lets say sheeting is to use blue tape to protect the areas you don't want touched and use a rough grit like 100 to tear into the glue you have to be real careful I usually use a sanding block,some extra balsa wrapped in sand paper works well, the rough stuff will make short work of balsa wood and hardly a dent in the CA but the blue tape will protect the surrounding balsa from over sanding.