To make a paper piping bag, take a square of greaseproof paper, about 35 x 35cm (14 x 14 inches), and fold one corner over to the opposite corner. Cut the fold in half to form a triangle.
Take one of the paper triangles and hold it with your left hand at the middle of the longest side and with the right hand at the corner on the opposite side.
Now move your left hand over to the right corner and curl it over to the top corner, so that it forms a cone.
Now move your right hand to the left corner and roll it around the cone until all the corners meet at the top of the cone. Adjust the corners by moving them back and forth between your fingers until the cone forms a sharp point (see above picture).
Fold the corners inside several times to hold this shape. Only half fill the piping bag with icing and close by folding the side with the seam over the plain side twice.