Basic Armor Patterning

Basic Armor Patterning

The art of patterning costume armor is difficult to teach. It requires a good understanding of how a 3-D shape can be formed from 2-D surfaces, which is best learned by experience. That said, I can share some tips to get you started.


Stiff paper. Construction paper works for me. Tagboard is another good choice. You want something cheap that has some heft and stiffness to it.
Tape, measuring implements, scissors, pens and/or pencils.

The Process

1) Draw your best guess at the basic shape of the piece.

For chest armor, lay out a well-fitting non-stretchy shirt. Trace the arm and neck holes and shoulder and side seams. You will wind up with something that looks similar to a pattern for sewing a shirt. It may also help to search armoring and costume howto sites for armor with the same basic shape as yours. Googling armor pattern will give you quite a few links to look through.

For something made of a simple curved plate, try to measure the size of the object on you or just guesstimate the dimensions of the plate. Common geometric solids – spheres, pyramids, cylinders, cones, and so on – can be drafted mathematically, as explained later in the article.

If your piece has compound curves and doesn’t resemble any easily drafted shape, take your best guess at a shape that looks similar. In some cases, such as the Zhang He pauldron example explained later, a complex-seeming piece may consist of simpler shapes. There’s also the option of creating your own interpretation that has a similar overall effect but is easier to draft.

In any case, you can do what I refer to as Taper Mache. Find or make a form with a shape similar to the finished product. Tape strips of paper over it to cover the surface. Cut the result so it lies flat, and refine that into a pattern. Take care that the result is practical to construct with your material of choice. Thin slivers and precise cuts can be a real pain to join smoothly in thick foam.

2) Adjust the prototype until it works.

And now for the fun part. Expect to go through lots of paper and tape. This is not a waste of time – in fact, it’s quite educational. Every adjustment and every redone prototype will give you hands-on experience at understanding the process, which benefits you in the long run.

So, you say, what sort of adjustments am I supposed to be doing? Well – is the piece too long? Too short? Does your breastplate pop out weirdly at the top? (If so, it’s probably too narrow, so split it down the middle and tape in a strip of paper.) Does it fit badly because you have curves and it doesn’t? (If the paper doesn’t bend around you in the right way, you may have to experiment with darts and/or gussets. For ideas on how this works, look at women’s shirt patterns.) Are the armholes or neck opening too baggy or constricted?

If you’re trying to wrangle a 3-D shape into something closer to the final shape, you have to figure out why it looks wrong and what you need to add or remove in order to fix that. It’s very much a trial and error process.

How to Pattern Basic Geometric Solids

Some 3-D objects, like rectangular boxes and cylinders, are straightforward. Here’s some help with the ones that involve math and possibly non-intuitive shapes.


A cone pattern looks like Pac-Man – a circle with a wedge cut out of it. For a finished cone with base radius r and height h:

  1. Find the length of the slant s. According to the Pythagorean Theorem, s = sqrt(r2 + h2)
  2. Draw a circle with radius s. Mark its center.
  3. Calculate the angle of the wedge to remove. We know that the wedge will close to form a base with a circumference of 2πr, so the angle = 360 * (2π * s – 2π * r) / 2π * s
  4. Draw the wedge.

For a truncated cone with a hole in the top, simply cut a circle of appropriate size from the center of the pattern. Of course, you’ll need to calculate the height of the original cone if you don’t already know it.


This one’s fun, and it’s a good illustration of a way to pattern compound curves. Take a look at a globe. Notice how the equator and lines of longitude form petals that meet at the poles. The following instructions will produce a flat-bottomed petal – a sliver of a sphere. (If you want to make an entire sphere, you can simply mirror the petal around the bottom edge.)

Eight petals (four for each half of the sphere) will get you a pretty smooth curve without driving you too nutzoid from joining finicky seams. Given a sphere radius of r, we know the following about each petal:

– The bottom edge must measure 2π * r/8, or π * r/4
– The distance from bottom to top must measure 2π * r/4, or π * r/2
– The top must come to a point with an angle of 360/8 = 45 degrees


  1. Measure the width and height of the petal.
  2. Draw the center line and a 45-degree angle centered at the top.
  3. Draw lines on each end of the base that are perpendicular to the base.
  4. Connect the base edge and top angle with a smooth curve.

When you cut out the piece, fold it along the center line first so that the curve will be identical on both sides.

You could make an ellipsoid from similar petals, but that would involve more math and effort. For one thing, if the horizontal cross section is an ellipse, the petals will not all be identical. You’d be best off starting this by taping a rough cover over a blown-up balloon or similar object.

Example of Guess and Check Patterning

Inspired by some spiffy-looking Japanese cosplayers’ armor, I set about trying to draft a pattern for my new Zhang He pauldrons. Achieving something truly accurate to the reference art (a bell with an outwardly flared bottom edge) is beyond me, so I decided to go for an approximation similar to the other cosplayers’ work.

  1. At this stage, I wanted a shape that fit over my shoulder well enough for me to try on. From my rough measurements, I knew that the prototype would have a diameter of approximately 8″. I grabbed a nearby frisbee that was somewhat larger and used it to trace a circle. Then, I slit the circle and pulled one edge over the other until I liked the height of the resultant cone. This sort of dart previewing saves a lot of time otherwise wasted on cutting paper out and grafting it back in.
  2. Since the cone was a good enough initial estimate, I folded it into quadrants and futzed with the edge of the piece to create something that looked like the offspring of a cone and a pyramid. I had now replicated the simpler pauldron design that I had liked.
  3. I then decided see if I could improve on that. The bottom half of the piece had to angle down more sharply in order to follow my upper arm, while the angle of the top half stayed the same so it would ride over my trapezius. To accomplish this, I slit the seam that went down over my upper arm and overlapped it to effectively take out a wedge, just as I did with the initial cone.
  4. I widened the piece horizontally to make it look more like a pauldron. It was horizontally symmetrical, so I slit it down the center and grafted in a 2″ wide strip of paper.
  5. I messed with the edge again so it was scalloped similarly to Zhang He’s armor.
  6. I decided the piece should be somewhat wider. I cut away one of the “lobes”, added 1/2″ to the outer edge, and used it to create a new pattern with a 2 1/2″ center strip.

Pauldron and Pattern

Here is the resulting pattern along with an unpainted pauldron. Though the swirly embellishment crosses a dart, I was able to cut it as one piece. The openness of the design allowed it to bend over the curve of the pauldron.