I read something recenty about making spindle halves by glueing up two pieces of stock with a sheet of kraft paper (brown shopping bag paper) in between. Let it cure, turn it, when you're done, you can separate the two pieces by tapping it apart with a chisel, then the kraft paper will easily scrape / sand off.
I'd bet that this method would work well for bowls, too. You could glue up an extra bottom (if you're already laminating), or glue one to your chunk (if you're not laminating).
Haven't tried it myself, but I might have to if my new chuck doesn't get here before my impatience sets in. :P