Bob's exactly right. No need to spend a bunch of money for hollowing ornaments. Now we tell ya huh?
I just used an old hex key and turned a handle from walnut, and used a copper tubing cutoff for the ferule. Works great! Well... except for that one time...
Make sure to bend the tool so that there's a goose neck and the tip of the tool lines up with the axis of the handle. Otherwise the right angle of the tool, the ornament that hangs up, and lathe rotation have the mechanical advantage on you, which can result in some fairly spectacular things such as pinched fingers and exploding ornament globes.... don't ask me how I know this.
You can also see my extensive acorn birdhouse (and eyelet) tutorial here (for the time being, the webmaster keeps moving it):
http://www.classiccitywoodturners.com/D ... yelets.pdf