Mason Jars Work Great!
As long as you don’t keep them air tight. Over time, yeast will still produce small amounts of Co2. This buildup, in such a small space, can happen quickly and doesn’t take much gas to build up a considerable amount of pressure. Fortunately for myself, I haven’t had an explosion, but I have noticed a lot of my jars started to pop the top.
As the top becomes bent and the seal gets loose, Co2 is released. This happens to cause the yeast to expand and sometimes foam. Which has led to many of my jars leaking all over the place.
Put a hole in the top! Some leave the lids on loose, but I always feared tipping the jar over and losing the entire harvest. Putting a hole in the top minimized that while leaving a space for excess Co2 to be released. To keep the buggins out, just slap a piece of tape on top. This still allows for the gasses to release, but anything big from getting in.
Slap a little tape on top
Now you have a safe and cost effective way of storing yeast!