Especially now that it's Holiday Baking Go Time, my pastry bags constantly have some sort of colored icing in them. I'll supplement my pastry bag supply by making paper pastry bags for the less used colors. It's a great thing to know how to make, especially if you are making up lots of small batches of different colors and frankly, if you don’t want to wash your pastry bag every time you need to switch to a new color.
Start with a rectangular piece of paper. If you buy yours on a roll, make sure you cut the piece shorter than it is wide. The sheet I'm starting with is 16 x 24 inches. My example is for a half-cup's worth of filling.
Fold and cut your paper in half if you want to hold approximately one-cup's worth. Fold and cut in half again for a half-cup's worth. Fold the paper diagonally, from corner to corner, and cut. You will have a scalene-shaped triangle.
Place the longest side facing away from you, the 90-degree corner facing you. The very acute corner (A) should be in your dominant hand (mine's the right hand). Fold the corner into your hand and roll it towards the center; creating a cone, its point in the center of the longest side. Lift the other corner and wrap it over and around the cone you just made. The second corner (B) should line up with the 90-degree corner (C). Fold those two corners (B, C) inward, about an inch down from the point. Make a small tear and fold one half of the tear outward and the other one inward. Turn the cone around and using the edge of the cone, fold the extra paper from acute corner (A) directly over the edge of the cone. Repeat the tearing and folding back of flaps. There! You just made a paper pastry bag! When you fill your paper pastry bag, be sure to leave some headroom to fold the top down by at least two folds - otherwise your precious filling will come oozing out the top. Now go pipe something!