Mature Coconut/s It's best to choose one's that have slightly flatter ends to balance easier and nicely round-shaped. Plus, ones that don't have too much of the outer fibrous husk.
Small handsaw can be bought very cheaply online or from local DIY stores.
Sandpaper coarse and medium grit works best.
A brush
Linseed Oil - or any food-safe medium that will lacquer/waterproof the coconut bowls. Other options include generic vegetable oil, walnut oil, or even Extra Virgin coconut oil. Food-grade mineral oil mixed with beeswax is suitable for items you plan to wash a lot. You can also use any DIY store lacquer for bowls that won't be used for food purposes.
Instructions
First, open the coconut. When making bowls, it's best to use a small handsaw to cut the coconut precisely in the middle. Many other methods of opening the coconut, may end up in uneven sides. However, if that's not a worry for you, then use whatever process you prefer.
If using a handsaw, place the coconut on a kitchen towel or softer surface to stop it from rolling away. Hold one end of the coconut (not near the saw!) and then begin to push the handsaw back and forth slowly.
When you've managed to saw an inch or two into the coconut, turn it over and lightly pull at the cut to drain the coconut water into a bowl (save this to drink!). Continue to saw the coconut all the way through.
Next, remove the coconut meat. You can use a butter knife or other 'blunt' ended knife to slot between the coconut meat and shell. Work your way around the coconut, prying the meat away from the shell, and eventually, it will come loose.
Alternatively, you can get specific 'coconut tools' to remove the coconut meat. But that's only really worth it if this is an ingredient you work with often.
Once the meat is free, then you can use this to make shredded coconut, coconut flakes, or pretty much any of the other coconut DIYs mentioned above.
Now, it's time to sand the coconut bowls. Use sandpaper to sand the entire surface of the shell halves, until smooth. This includes the 'rim' of the bowl. You can use medium-grit sandpaper for the outside of the bowl and work very lightly if you don't want to ruin too much of the natural pattern.
Finally, lacquer the bowl to make it food-safe. Brush some linseed oil (or your lacquer of choice) on both the inside and the outside of the bowls*. You will need to repeat this step 4-5 times, drying in between, to seal it and make the bowl food safe completely.After each layer of linseed oil, you can leave it to dry out at room temperature or accelerate the process in the oven. Your bowls are now ready to use!
Video
Notes
*For a more natural finish, you can just polish the inside of the bowl.Caring For The Coconut Bowls:
Wash the bowl in lukewarm soapy water only. They aren't dishwasher safe and shouldn't be 'soaked' in hot water for long periods.
Never place in the oven, microwave, or fridge. 'extreme' temperatures can cause it to crack/damage.
The bowls can be used with hot and cold foods.
Over time the bowl will lose its sheen and oil coating. Simply, use another tablespoon of oil and polish the bowl, allow it to dry, and repeat once more. Voila!