>How about the best way to finish it, so that it is good and flat
>black on the inside
I have used the sawdust method I read about in S&T with good results -- I painted the inside with watered-down Elmer's glue, threw in sawdust and rolled it around, and then soaked it with flat black paint.
The result looks good -- it is very dark down there now -- but is not terribly durable. Except for a few inches at each end, I didn't vacuum or brush off the sawdust, and/or I could have used more paint, to really soak it well, but it seems much rougher and darker this way. It is really only a problem if I reach in, and brush against the sides.
As far as cutting and finishing, I just used a hand saw, and sprayed the outside after light sanding. It only looks funny during the day -- while in use, it looks beautiful.
Take care, Peter Augello