On Sat, 20 Mar 2010 06:28:46 -0700 (PDT), KOS
wrote:

Hi, i just installed some crown molding in a room very long piece
25-35 feet. I had to cut it in two pieces.. The smaller piece where I
cut it is like 2 feet... But when I join it, (like a puzzle piece)
there is a pretty big gap there. Quite obvious, even when I paint it
it will show, what should I do???

Did you bevel the butt joints at 45°, so they mate up? Or are you
speaking of corners ( In /Out ) that are not square corners in any
home?

I would avoid the plaster, joint-compound and especially the foam
ideas. If you must caulk this eye sore, use an "acrylic latex"
painter's caulk. It will flex and not crack from expansion and
contraction. But them again, what is the material? MDF or Oak?