Temper a small bowl of white chocolate, and in a separate bowl temper some dark chocolate. ( If you don't know how to temper, you can check out my post on How To Temper Chocolate. )
Cut some strips of acetate about the length of your mango mousse cake. You only need one but it is good to have extra in case you make a mistake.
Pour your white tempered chocolate over the sheets of acetate.
Place a strip of parchment on top of the melted chocolate. This will prevent the chocolate from sticking to your cake ring.
Wrap the chocolate strip around a cake ring similar to the size of your mango mousse cake.
Make sure the two ends overlap and tape the ends together.
Next, prepare a piping bag and fill it with some tempered dark chocolate.
Pipe chocolate into your polycarbonate mold cavities. Fill each cavity to the top and give the mold a few taps to pop air bubbles and make sure the chocolate reaches every part of the cavity. You only need to make two or as many as you'd like.
Once you fill your cavities, place some parchment underneath the mold and flip the mold over to dump out leftover chocolate.
Tap the sides of the mold with a bench scraper or spatula to remove all the access chocolate.
Scrape the excess chocolate off the mold with a scraper to enure the chocolates will have flat edges.
Place the mold upside down on parchment and leave to set.
Once the dark chocolate is set, repeat the process with the white chocolate to create a coconut shape making sure to pour the white chocolate into the dark chocolate. Leave to set again.
Un-mold the chocolate shells. Then using a warm plate or bottom of a small pot, warm the bottom edges of the bon bons to clean up the bottom and smooth it out.
Take a wire brush to create small lines and rough edges on the coconut shells.
Place the white part of the coconut in some coconut flakes. You can now glaze and decorate your cake.