Interesting. Sorry to hear about the loss of your shells.
BTW I haven't seen a proper shell for sale online. All the ones I've seen are just barely sanded and as thick as they were when they fell out of the tree.
A proper bilo (fijian: literally cup, but also the name of kava shells) should be ground down until it's really thin and light. I remember two separate years in primary school (ages 6 to 12) where everyone in my class had to make one.
Step 1: Find a well shaped nut and cut it in half. If you know the proper way, it can be done cleanly with a knife or sharp rock. Otherwise, use a hacksaw. Remove the meat/flesh.
Step 2: Smash a
Fiji Bitter bottle to get a nice piece of glass. These bottles work best because they're made of very thick glass.
Step 3: Use the glass to scrape the shell until it's thin enough that you're worried you'll crush it in your hands. Then sandpaper till smooth.
Step 4: Bury it in a swamp for 2-4 months. When you dig it up, it should have darkened significantly, be black if the conditions were right.
If all went well, you should have a perfect bilo.
I'm sure a woodworker would know a way to get the same result without burying the shell in mud, but that's the primitive way it was done when I was a wee boy, and that's still how it's done out in the villages of Fiji.
