Headlamp diffuser for LZZ-186

I have this headlamp: http://dx.com/p/lzz-186-600lm-1-cree-xm-l-u2-3-mode-cool-white-light-zooming-headlamp-black-1-x-18650-221722
and I have decided to build a diffuser for it, in order to be able to obtain even wider beam. It is useful for looking into the map, hanging the headlamp w/diffuser from the tree branch in order to illuminate a wider area, etc.

The diffuser has a clip so that it can be carried near the hedlamp itself even when not in use.