50 grams of the finest copper wool made of pure copper thread. If you fill the vapour chamber of your still with this copper wool your distillate goes through a purification process. More hydrogen sulphide bonds to it, which results in a milder flavour - and you can distil high-proof alcohol since you increase the rectification effect (just as with raschig rings).
It is also suitable for self-made stainless steel stills. During alcohol distillation the vapour should always flow through the copper material. This copper wool also helps a stainless steel still to process the hydrogen sulphide.