I take cardboard boxes from work that are gonna be thrown out and use them. Just cut a few holes in the side and leave the top open. I fill them and then store in a ventilated but dry place. For me, that's the backyard shed. It isn't air tight and breathes well but keeps the rain out.
18.5" OTS, 22.5" OTG, CB Silver(Rip), Vintage Coleman Bullet, Pit Barrel, UDS