Walk.....First ,check w/ the post office in Canada ,assuming there is no problem w/shipping something labeled "powder flask", If it has actually had powder in it , but has been emptied completely , it may still have detectable powder residue , dust , inside. A tablespoon of coarse sand shaken in it a couple times should remove most powder residue , if post office declares residue as a problem. You never know how kookie some laws are written. I wouldn't just ship it w/o researching the rules. M/l catalogs have flasks to buy new and there is no restrictions on shipping them. ..oldwood