Use the wood burning tool to cut off the nub of the plastic ornament
Cut the foam, shaping it into a small cube
Write your answers one each side of the cube with the fabric paint. Do this in stages since you want to make sure each side is dry before flipping it over to write on the opposite side. Set aside to dry.
Apply the water resistant glue to the edge of half of the fillable ornament
Place the cube inside and seal the halves of the ornament together. Let it dry according to your glue's instructions (this could be 24 hours).
Use the wood burner to poke a small hole into the ornament
Fill the ornament with water. You can do so by submerging it in a bowl of water or using an eyedropper
Use the wood burner to melt the edges of the hole back together as best you can
Use a glue gun to seal any remaining space
Paint the ball with the black fabric paint so it's completely opaque, except for a small section that's wide enough to read the answer.
Let dry
Video
Notes
Tip: When painting, use a plastic bottle cap or similar object that is the size of your answers and place the ball on it. This will allow you to paint all around, while leaving that part unpainted.You may also need to do multiple layers of paint to make sure it's completely opaque.