Cyanide is a good way to ctb. Like @Dutch said it can be extracted from cherry seeds or even apple seeds.
Buying cyanide is easy. It comes in many forms, hydrogen cyanide, sodium cyanide, thiocyanate, isocyanide, etc. Cyanide is lethal in almost any dose. Although in small doses it could take up to 24 hours to die. Doses for hydrogen cyanide, for example, range between 100ppm to 2000ppm. The bigger the dose the quicker the death. I've heard of high doses taking as little as ten seconds to kill.
Cyanide kills buy creating what is called histotoxic hypoxia. It kills by not letting cells in your body absorb oxygen. The cyanide attaches to your bloods protein molecules creating a block that inhibits the cells reaction to oxygen. Organs in your body like the heart and brain depend more on oxygen to survive so they're the first affected. Which is good news for us cause when the heart and brain go so do we.
Cyanide works just like SN. It basically renders you unconscious fast then begins to starve your body of oxygen. Essentially suffocating you. And there usually isn't any vomiting so no need for antiemetics.
People day cyanide poisoning is painful. That is a lie. Even in small doses where you don't die right away you won't feel pain. What happens is you become lethargic, have shallow breathing and your pulse and bp drop. So in the face of those theories that say it is painful are wrong.
Cyanide can easily be bought from experimental chemical companies. But that might raise suspicion from law enforcement. Or it can be bought off the dark web. Or it can be extracted. Or if you don't want to do any of these you can just simply chew some seeds.
I hope this helps. I really want you to know I love you. I care about you. And most importantly i understand you and I support you.
Love ya,
Centerism