Introduction: One Cut Origami Star

About: The BYU Compliant Mechanisms Research Group (CMR) involves students and faculty who strive to make an impact by creating compliant mechanism theories and applications that are novel, used by others, and make a…

In this Instructable, you will be making a symmetrical 5 pointed star with only 1 straight cut. This is known as one cut origami. One cut origami (also known as one-cut, fold-and-cut, and magic cut) is a form of origami where you fold up a piece of paper, make one straight cut, then unfold the paper. Mathematical researchers have shown that any set of straight lines on a paper can be cut using this technique (with no extra cuts). Although technically every set of straight lines is possible, patterns exist for a butterfly, swan, turtle, and all 26 letters of the alphabet.

This technique was used in magic tricks by Houdini (and others). It is also rumored that Betsy Ross used this same fold pattern to create the stars on the first american flag.

Step 1: Fold in Half (hamburger Style)

Here are the materials you'll need to complete this instructable:

  • 1 sheet of paper (8.5 x 11", also known as letter size)
  • 1 pair of scissors
  • 1 writing instrument (pen, pencil, marker, etc.)

First, fold the piece of paper in half, width-wise (hamburger style). Make sure that the corners line up well and that the crease is well-pressed (run your fingernail along it).

Step 2: Mark the Middle

For this next part we're not going to make a complete fold. Instead, we'll just be putting a slight crease to mark the middle of this folded section.

Take the folded paper and bend it in half again, this time length-wise (hot dog style). This bend should be parallel with the first fold. Align the two edges and crease the very edge of the paper, as shown in the picture (not along the whole length). This marks the midpoint between the edges of the paper and our first fold.

Use your writing utensil to mark where that crease is along the edge.

Step 3: Diagonal Fold

Fold the top creased corner (the side with the folded edge) down to the mark you made in the last step. This should create a diagonal fold across the top of the paper. Press this crease firmly.

Step 4: Fold Over Large Triangle

Your paper should now look like a quadrilateral section on top and two triangle sections on bottom. Fold the larger triangle section (the one that has a folded edge) over the creased edge, as shown in the picture. Press crease firmly.

Step 5: Fold Arrowhead in Half

Your paper should now look like an arrowhead (see the top left section of the image). Fold in half such that the two longest edges lie on top of one another. This fold should go along the edge of the flap that you folded in the last step.

The result should look like an ice-cream cone.

Step 6: Mark the Cut Line

With practice you'll be able to do the cut without marking. But for the first time...

Open up the fold you just created and find the corner of the paper (shown with the pencil in the top left image). Re-crease the fold and mark that location on the outside of the paper. This is where you'll start your cut.

On the opposite long edge, measure about 3-4cm from the point and make a mark (we've found that around 4cm gets the best looking star). This is where you'll end/start your cut.

Draw a straight line between the marks that you've made.

Step 7: Cut and Unfold

Cut along the straight line. This cut should go through all layers of the folded paper.

Unfold both pieces. You should now have a 5 pointed star and a matching stencil.

By changing the angle and location of the cut you can get different types of stars. In order to get the stars flat, iron them on a low heat setting or put them under heavy books for a while.

There are 10 cut edges to the star, but you only had to make 1 straight cut. Pretty amazing, huh? You could almost say it is magic. :)