Do you mean the windows surrounding it? If you're talking about the holes in the barrels - try using a machinsts drill bit that is a little smaller than the barrel itself. Or,you could try to machine the ends with an exacto blade,very carefully turning it inside the center of the barrel until it makes a small indentation. Then,you could paint it black on the end to make it look deep. If this sounds like too much trouble,you could just paint it flat black.
