I also usually turn the bottoms later. But for those few times that
I don't, or when I've turned something like an egg (that doesn't have
a bottom), I made a couple of very simple jigs to hold the piece. It
will hold a bowl face up, or hold an egg for spraying.
It's just 3 very small holes (~3/32 or so) in a scrap of flat wood
that hold half toothpicks broken in the middle, pointy end up.
The points are extremely small so they don't damage the finish, or
cause the oil to collect, and are easily replaced if broken.
If you combine this holder with a lazy-susan type base, you have a
perfect holder for spraying lacquer. And if you're making several
items (see eggs again), just put several 3-hole patterns in the board
and put an egg (or bowl) on each set.
Tom Weber in Merritt Island, FL