Creating this chunky pen from an old roll-on deodorant bottle will help to develop your child's knowledge and understanding of the world around them, and how things work - in this case, how ball-point pens work. The activity will also help to improve their hand-eye coordination and fine motor skills as they assemble the pen and then start drawing with it.
How to extend the magic
Make a set of ball-point pens in different colours and then get scribbling! Your child could create a swirly pattern or draw a picture of something - whatever they like. When they've finished their ball-point pen work of art, you could frame it and display it on the kitchen wall or in their bedroom.