Place the silicone mold on a flat, moveable surface like a tray or cutting board.
Place the chocolate in a microwave-safe container like a glass measuring cup and microwave at 50% power in 30-second intervals, stirring in between each time. Mine took about 2 full minutes total.
Add a heaping tablespoon of melted chocolate to each well of the silicone mold.
Using a small rubber spatula, offset spatula, or back of a spoon, spread the chocolate up the sides of the mold until completely coated.
Wait about 5 minutes for the chocolate to cool a bit and then divide the remaining chocolate between all of the wells and spread it around to give each of them a thicker coat. You want the chocolate to be thick, especially around the top edges.
Place the mold, while on the tray in the freezer for the chocolate to set for at least 30 minutes.
Once the chocolate has set, remove from the freezer. Give a little tug around the silicone mold to help release the chocolate. Then carefully use your fingers to push the chocolate cup out of the mold. Place the chocolate cups on a plate.
Place the drink mix, marshmallows, and any other add-ins you are including in 3 of the chocolate cups.
Working quickly (so your fingers don't melt the chocolate), place one of the empty cups open-side down on a hot plate to melt the edges a bit. Then place it on the filled half of the sphere and press lightly.
Melt the decorating chocolate the same way you melted the chocolate for the spheres and then transfer it to a piping bag or decorating squeeze bottle.
Pipe a thin ribbon of chocolate around the seam of the spheres and then smooth it out with your finger.
Then drizzle the melted chocolate over the tops of the bombs and sprinkle with decorations.
Allow the chocolate to set before moving.
Keep refrigerated or frozen until ready to use.