needle and thread
scissors
pencils
buttons
felt
Put the phone on the felt and cut a rectangle of the felt 2cm larger. Cut rhe bottom corners into curves.
Place the front piece you have just cut out onto the felt you will be using for the back and draw around it. Add 1/2cm to the top edge, and then draw a triangle about 4cm tall on top of that (to form the flap).
Cut two wings and sew them to the front piece of felt.
Sew the two buttons and They need to be symmetrical.
Lay the front and back pieces together and blanket stitch around the edge.