I suggest using acrylic sheets, thin ones. If you have the skill, try and make a dome shape for the top.
If yo didn't already have the hilt then I would have suggested using a clear, paper thin material that you could inflate with air that would retract into the hilt. This would give you a nice woosh sound. It may be inaccurate, but baby steps. The problems with this would be finding a thin enough material that would also be able to move while staying parallel to the hilt. For that you might need to use small metal 'arms' that would extend when turned on. This is just brief ideas of course.
And you already have your hilt so it's pointless... kinda.