Perhaps, but I'd say you are in a grey area at best. I might recommend writing to the BATFE FTB, and get an opinion letter to cover your butt before you make such a device. Since the ATF's definition of "AOW" explicitly includes the term "cane gun", I wouldn't risk it myself. It looks like a cane, and it is a gun, therefore "cane gun" a prosecutor may reason.
You can write to:
Bureau of Alcohol, Tobacco, Firearms, and Explosives
Firearms Technology Branch
244 Needy Road
Martinsburg, West Virginia 25405 USA