Agar and liquid culture
Where a culture gets cleaned up and multiplied. The fiddliest kit on the list, and the one that pays for itself, because everything downstream inherits whatever you let through here.
Petri dishes or agar jars
Holds a thin layer of nutrient jelly for the mycelium to run across in plain sight.
Why: A flat plate is the only place you can actually see what a culture is doing before you commit a jar of grain to it.
Improvised: Small glass jars with a shallow layer of agar in the bottom can be pressure cooked and used again, which plastic dishes cannot.
Agar powder
Sets the nutrient liquid into a firm jelly once it has cooled.
Why: It is the setting agent and nothing else. The food comes from what you dissolve in with it, which is why the recipes are always agar plus something.
Improvised: Culinary agar agar from a food shop sets at the same rate if the grade is fine enough to dissolve cleanly.
Light malt extract
The sugar the culture actually eats on a plate or in a jar of liquid.
Why: Light rather than dark, because dark extract stains the medium and makes it harder to spot the first flush of colour that tells you something has gone wrong.
Improvised: Any light dried malt extract from a homebrew supplier is the identical product at a better price.
Scales that read to 0.1 g
Weighs agar and extract for a repeatable recipe.
Why: Agar recipes are grams per litre, and eyeballing them gives you a plate that is either soup or rubber. Being able to repeat a batch is most of the point.
Improvised: Kitchen scales that read to a gram will get you a workable plate, they will just not get you the same plate twice.
Injection port lids
Lets a needle in and out of a sealed jar without opening it.
Why: A self healing port means a jar of liquid culture is opened once, at the very beginning, and never again.
Improvised: A hole in a lid filled with high temperature silicone, cured completely before it goes anywhere near a pressure cooker, is the homemade equivalent.
Synthetic filter discs
Lets a sealed jar breathe without letting anything in.
Why: Liquid culture needs gas exchange while it is on the stirrer, and a filter disc is the difference between a jar that keeps working and a jar that goes sour.
Improvised: A square of micropore tape over a drilled hole does the same for a jar you intend to use soon rather than store.
Syringes and needles
Moves liquid between vessels through a port, without opening either one.
Why: Needles are single use in practice. They blunt quickly and a blunt needle cores the rubber of the port instead of piercing it.