Snip the tip off a corner of a plastic bag to easily transform a resealable plastic bag or plastic grocery bag into a piping bag. Adding a tip to the opening gives more professional-looking results, although it is also possible to pipe the icing without using a decorating tip.
Alternatively, unroll baking paper and fold one end over to make a triangle. Cut the triangle from the roll, and unfold it to make a square. Cut along the crease, transforming the square into two triangles. Lay one on top of the other, and bring one corner into the apex of the triangle, rolling the paper up and around to form a cone-like shape. Hold that side in place, and bring the other side around, folding the top over to hold it in place, or staple it in place to keep the paper together. Cut the end off the bag, and place a pastry piping nozzle into the opening. Fill the bag with icing, and begin piping it onto cakes and other baked goods.
Use different tips to change up the results. Round tips are idea for outlining, filling and writing while leaf and flower tips make it easy to create decorative flowers.