Spaulders are traditional armor pieces covering the shoulders and upper arms. Few pieces of armor proclaim "Badass" with such clarity. A breastplate may be covering a beer belly and a helmet is not suitable for a driver's license picture, but rest assured, spaulders can compliment a variety of ensembles to proclaim: "Mess not with me." Leather spaulders in particular will even make it past airport security without issue.
I make all my spaulders at TechShop.

Gather:

Heavy leather (3 square feet makes a pair of spaulders of three layers)
Rivets
Upholstery thread
Shears, razor, or some other leather-cutting tool
Hammer

Step 1: The Making of the Pattern

Leather is expensive, so I made a single spaulder of scrap vinyl to refine the shape. The two bottom layers have increasingly deep darts to achieve a compound shape, hugging the shoulders. These are leaf-shaped, but spaulders can also be round or square.

Step 2: The Cutting of the Leather

With the right shape, I now take-apart the vinyl test-spaulder and trace its shape on the hide. Repeat each edge, to maintain a symmetrical profile. Now cut.

Step 3: A Riveting Process

Segmented armor can be joined near both edges or along the center. This will affect how the pieces respond to movement. With larger pieces it is ideal to put the pivot points close to the natural joints of the wearer. For these, however, the layers will be joined along their center line. I am using 1/4" brass cap rivets for this, set with a ball-pein hammer.

Step 4: Complete!

Depending on the use and application, you may wish to experiment with different ways to attach your spaulders. Here I have tied the three layers together with a strip of leather which will stitch onto a coat.