Two suggestions. One is fiberglas (heavy) and one is carbon fiber (light).
For fiberglas, go to a camping supply store and buy a tent pole repair kit. Typically they contain some sections of fiberglas poles with ferrules so that they can be pieced together. You want to think about the various pole section lengths so that you end up with 45", probably from two sections. Then make an extra section that is 5", and shock cord them together. You can stick all three sections together to get 50", or you can pull the 5" section loose and let it flap. That gives you 45".
You can do the same thing, roughly, with carbon fiber sections from Fibraplex. $$$