Air filter / gas exchange for mushroom fruiting bags.

It's a small plug to fill with polyfill and insert into the mushroom bags for fruiting. (Not for colonization.)

I know most people use bags with built-in filters or pierce their bags with a needle, and this plug crosses the line into overengineering, but I use large Ziploc bags for fruiting because they're cheaper and my house has some moisture and mold (water leaks), so this ensures a little more sterility than making small holes.

It's easily inserted thanks to its sharp tip, both in empty bags and in already colonized ones.With the plugs, there's no need to leave the bag open or add polyfill to the zipper corner, as it now works like a small monotube.

It stays tight and watertight around its outer diameter.

Since they're very small, they can be used once (not a huge cost, just 3 grams), but they can be reused if you wash them by shaking them in a container with Lysol, bleach, or alcohol.

You can insert as many as you need; for an 8L bag, I only use 4 plugs, 2 cm above the casing. It depends on the amount of air exchange you want.

You can use PLA, but since it's biodegradable, they will eventually disintegrate. It's better to use PETG if you want to reuse them.

(Yes, the image above with the full bag only has dry grain, just to show how it would look.)