No no, not the car kind of 'mobile' or the phone kind of 'mobile' - this is the hanging from the ceiling kind of 'mobile'.
You will need: twigs, sticks, paint, fishing line.
Paint the twigs, hang them from a bigger stick using thread or fishing line, hang from the ceiling, watch them turn in the breeze.
Oh and guess what? .. 8 days till Christmas!
For more of such fun visit KEDUBLOCK