Cutting Kydex can be done in a number of ways, ranging from easy to difficult to dangerous. In my opinion, the best way to do it is with a Band Saw and the most dangerous way is with a circular saw (see bottom).

The bandsaw leaves a clean edge, cuts rather than melts, and is extremely controlable. With the bandsaw, you can cut fairly tight turns, and by using the guide fence allows you to true up your project after forming.

Jigsaws will also cut Kydex fairly well, but you do have to clamp it down to a surface, and have a way of cutting the Kydex without cutting the surface that it is clamped to.

You can also use hand tools like a hack saw to cut the Kydex, but this can be difficult if it is not held stable. The Kydex tends to flex all over the place rather than cut. This is the same problem with using the Jigsaw.

Another option is a dremel tool with cuttoff wheel. This works fairly well, but does tend to melt the edges, even at very low speed. This isn't much of a problem, just another step to add to cut of the melted debris with a razor. As shown in the image of the dremel cutting, it's very important to lay out all the lines where you need to cut, in order to see them well while cutting, and to maintain a consistant edge.

The Cheapest tool for cutting kydex is a razor knife. Simply score the Kydex a few times, and then bend and snap it apart. This obviously only works for straight edges, and if you have to cut portions out from a sheet, it may be difficult to conserve as much material as possible.

At the top of the article I mentioned that the circular saw was dangerous. What tends to happen with this is the spring of the kydex starts modulating as the blade hits it, and if it reaches the right frequency it will become unpredictable, hit a tooth at the wrong angle and fly. It doesn't happen every time, but there is definitly the possibility. This was my prefered method until it happened to me!