If you ever wanted to know how to make a shotgun shell goose call, here's how: Take a spent shell (3" works best) and burn a dime sized hole about in the middle.
Using it is a whole different story. Place it lengthwise between your cupped hands so that one hand is covering the open end of the shell. Make sure the hole you just burned is facing up so you can blow into it. Now you have to play with the positioning or else it'll sound like a train whistle instead of any type of goose call. You must get that er-ut sound regular goose calls make, it should be higher pitched. Takes a lot of practice yes, but I'm able to call in cackler's, and speckle bellies with them. I wish I had illustrations so I didn't have to explain so much.
(p.s. I don't think this'll make it as a magazine tip, but thought I'd share it and maybe 1-2 other people would figure it out with my poor explanitory skills)
(p.s.s Act like you're blowing into a bottle. Your tongue should act like your saying "what" but blowing into the "bottle")