If you spend any time in the turning community, you’ve probably seen this style of ornament before. The hollow urchin shells are available online (and in various species—the smoother ones are thinner and more delicate).
The key to a good-looking urchin shell ornament is to make sure the finials are thin and delicate. Otherwise, the entire thing looks clunky instead of sleek and elegant.
To ensure a striking-look, choose a tight grained, dense wood that won’t distract from the design. Here, I’m using ebony. Start by measuring both openings in the shell with calipers. On the top and bottom, you’ll be turning tenons that fits inside the opening. I put the larger opening to the bottom.
I turn the finials in three parts. In the photo below, you can see the top of the ornament. This is simply a piece with a tenon, sized for the hole in the shell and a sweeping cove cut, capping off in a dome.