What Is A Shotgun Fruiting Chamber? A shotgun fruiting chamber is a low-cost method to keep the humidity consistently high while still providing fresh air to the mushrooms. It consists of a tub with pre-drilled holes on all sides except for the lid. This is to encourage air flow. Simply add a layer of Perlite (Included) and hydrate with water (not dripping wet), when you fruit your PF Tek kits simply place them on a piece of tinfoil or wax paper on top of the perlite, keep the sides misted and fan 2/3 times a day to promote humidity.