Mike, I've had pretty good luck with hoof material as a 'supplement', it does indeed stink because it is a natural carbon material....I didn't find the smell that radical though....(not like Auschwitz or anything).... I did clean it, saw it and place it properly against the outside walls of the crucible.....JMO.....

The leather and horn are old recipes like the hoof material, the other stuff you mention are all over the top I think.....

Best,

Doug