If you're going to do it in jars, finger tighten the lids, the pressure will "push" out, but the outside pressure won't be able to "push" in.
Last batch I did turned out amazing, I did them in a LARGE fido jar. Left it sealed the entire time. The rubber flexes enough to let the gas out, but not outside air in. This Link for tests on a bunch of different types of jars.