Step 1: Things you need
1) Coconut shell (cut into 2 pieces),
2) Silicon carbide paper (aka, sand paper)
3) Drill machine or anything to make small holes on the shell,
5) Lock system (in this case, hasp and staple's the best)
6) Screws and screw driver,
7) Varnish and 1 inch paint brush,
8) Small padlock.
(I couldn't gather all the materials at the same time, so couldn't take a picture of them together)
Step 2: Getting started
You'll need 1 coconut to make 1 jewelry box.
After breaking the coconut into 2 pieces (the pieces should be relatively equal), use a silicon carbide paper to get a smooth finishing. Take a small piece of silicon carbide paper and use the rough side to get the smooth finishing on the shells (for both inside and outside of the sells).
I popped a hole to drain the coconut water, so I had to cover the hole with a thick brown paper and white glue.
I also applied a coat of varnish on both pieces in this step.