Ready for some geometry? Of course I wasn’t going to skip my favorite, the polyhedrons! This is a technique you can find in Pattern Magic 3.
I don’t know about you, but I’ve never really liked mathematics, so it took me some time to understand how to calculate the pattern. I’ve put together a tutorial, trying to explain everything in the easiest way possible, using lots of drawings. Never mind the terms, not sure I used the official ones!
In addition to the usual tools ruler and pencil, you’ll also need a compass.
1. Let’s get started by drawing any kind of polygon, regular or irregular, with as many angles as you want. Mine is an irregular triangle. Then you’ll choose where you want the highest point to be (see the orange dot).
2. Draw lines from each angle to the central dot. As a result, you now have many triangles. In my case three. Name or number each of them.
3. Now you’ll measure all the sides of your triangles. I separated the triangles to make it easier to understand, but you can do this in your original drawing. Only the outer edge is a final measurement (in black). The other ones still need another passage.
4. With the measurements you have now you can’t get a 3-dimensional result. You still have to consider the height of your polyhedron. So decide how high you want the highest point to be. I decided 5cm. Draw a 90 degree angle and mark the height at the vertical axis. All the other (=grey) measurements from your triangles go to the horizontal axis. Draw a line from each of them to your height-point and measure the lines to get the final measurements.
5. Almost done! Now you have all the measurements you need. You just have to put together the triangles again, using these measurements. First draw a line using the only measurement that remained the same from the beginning, namely the outer edge. Then pick up the new measurements with the compass from the previous drawing and find the point where the two measurements align to get a triangle.
6. The last thing to do, is to copy all the triangles together in right order. This is why you must name the pieces. Copy also the original flat polygon. You’ll need it as a base. The pattern is ready!
Just some quick notes about sewing. And btw, you’ll get better results by using a fusible interfacing, which I didn’t use here.
1. First close the polyhedron, leaving the amount of seam allowance open at the edge. Snip the other angle-tips, too. This will make it easier to attach the piece to its base.
2. Turn around and press all the facets. Be careful not to go over the tip of the polyhedron. Attach it on the base. Done!
Adding polyhedrons to a garment-pattern
With these instructions you can make all kinds of polyhedrons. When adding them to your pattern, just draw the shape where you want it to be. Then copy it/them from the pattern and make all the calculations as usual. Only thing to add, if you have many of them in one garment, are marks between the different pieces and giving a number or name to each so you’ll know which one goes where. Sometimes you can also absorb darts by placing the polyhedrons strategically.
To finish, here are two examples of patterns I’ve done. See for the finished pieces. The skirt was admittedly kind of crazy and it took me ages to calculate all the bits!