Like already mentioned there's no mega thread because stabbing oneself, and generally bleeding out, is probably one of the methods with the most amount of failure rate and pain and this forum's main focus is to offer guides on how to catch the bus in peaceful ways.
Still, personally i find this topic interesting, will have to dig through all my files to compile more stuff trying to contribute to a mega thread on this (which probably will take hours to finish so bare with me)
Just dropping a very brief little info guide about Harakiri, will add more later + other ways and data (although if choosing to die by the blade, disemboweling oneself has probably to be the most hardcore method of them all, would take an insane amount of dedication to not just do it but also not chicken out midway)