Very nice Bill! Bowls are kind of fun on the bot. No worries of catching the edge with the tool on that 'One last time' cut on the lathe. I've done some wedding platters and oval plates w/V-inlay.
Denis, look into the two rail sweep tool. I make the top or inside shape first with vectors for a two rail sweep that is half the bowl and then make another set of vectors that represent the bottom shape. These two sets of vectors are right next to each other and represent a cross section of the bowl/platter. I'd attach some pics, but don't want to hijack Bill's thread. Looks like Bill did his in approximately the same manner.