For pretend plays and concerts, there cannot be a quicker microphone idea than this one.
What you need
Toilet roll tube
Decorate the toilet roll with paint or crayons.
Take the aluminium foil and make a ball big enough to sit on top of one end of the toilet roll.
This is the microphone and the toilet roll is the handle.
Using tape or glue secure the aluminium ball to the tube.
Glue on some streamers for added decoration.
Let it dry and then start singing.