Fruiting and harvest
Conditions rather than kit, carried on through the harvest and the drying that follows. The list is short and the discipline is doing less than you want to.
Hygrometer
Reads humidity and temperature inside the chamber.
Why: Guessing at humidity is how a surface quietly dries out over three days. A cheap probe turns an argument into a number you can act on.
Improvised: A probe with a remote sensor lets you read it without opening the lid, which is the whole point.
Spray mister
Wets the walls and the air, not the mushrooms.
Why: Water sitting on young pins invites bacterial spotting. The bed holds its own water, so what you are topping up is the air around it.
Improvised: Any fine trigger mister that has never held anything but water.
Fresh air holes and filter tape
Lets carbon dioxide out and filtered air back in.
Why: Gas exchange is most of what triggers fruiting. It is also the thing most often overdone, which dries the surface and aborts pins.
Improvised: Cracking the lid on a schedule is the crude version and it costs you humidity every time.
Drying rack or a fan
Moves dry air over a harvest until it snaps rather than bends.
Why: Anything still leathery is still holding water, and water is what spoils a stored harvest. Air movement does this better than heat, which damages what you have grown.
Improvised: A wire cooling rack in front of a desk fan, out of direct sun, is the standard improvised version.
Airtight container and desiccant
Holds a dried harvest away from moisture and light.
Why: Desiccant finishes the job the air started and keeps it finished. A jar without it slowly re-absorbs whatever the room has.
Improvised: Silica gel sachets, dried in a low oven first, are the cheap and reusable version.
Scales
Records wet and dry weight for each flush.
Why: Numbers posted online are usually wet weight and usually unverifiable. Your own record, kept the same way every time, is the only comparison worth anything.
Improvised: The same scales from the agar stage, if they reach high enough.