A russian youtube machinist made an M40 bolt… with both left and right hand threads. The threads are clean enough that the nuts that size can self-thread under their own gravity… simultaneously in counter-rotating directions.
So, that’s witchcraft and I’m reporting it.
I have one of those workbenches just like his, i use it way more often then my other workbench where I stage tools and fasteners that I put away once in awhile and half finished projects that I fully intend on getting around to working on someday soon.
Threads were 10-start if I recall - a nice steep incline to drop.
Now I’ll be trying to print this:
Apparently inspired by the vid you posted