There's no really accessible, reliable, easy and painless method unfortunately, such a thing would be far too good to be true and if such a thing existed then this site would never need to exist. But there's a suicide resource complination on here for method research, if you came on this site looking for easy, straightforward answers as to ways to peacefully and reliably ctb then there aren't any to be found especially as we exist in such an anti-suicide society, if people could ctb easily with anything otc then those ways would be restricted. But anyway hope that you find the freedom that you are searching for, best wishes.