Cable ties around the scrotum. Use the tensioner tool to tighten ‘em up really good. Testes will die in about 10 minutes, and the pain unbearable when the ties are removed.
Read it on a book ...
I have a special set of stainless steel crushers that look like a cross between a pair of hedge clippers ad vise grips. They are for castrating steers and sheep. They do not leave any physical evidence, except that they crush the blood cord supplying blood to and from. In a week after use your nuts are atrophied into nothingness. A month later they are absorbed into the body.
Ok, I almost passed out reading your comment!