Kevlar is an incredibly strong material. So you need to pack many layers together to sew something effective out of kevlar. You have to tightly sandwich the layers together to make the best use of them. Sew x patterns all over your kevlar like you would in a quilt. Doing so will compress it. Kevlar resists high-speed, blunt objects, but it is not as effective against sharp low-speed objects like needles. There should be no problem with sewing this strong material. But you need to keep in mind that it is thicker than other fabrics. Remember that kevlar is a strong material, so you need to use either a heavy-duty sewing machine or an all-metal sewing machine. These machines will be much durable and can handle the extra stress of your kevlar. It will also be best if you use a canvas or jeans needle that is titanium-tipped. These tougher types of needles will be able to go through thick materials such as kevlar.