After I started this thread I received some messages with questions about Jack’s mechanisms. Answering here. His favorite hobbies are locking mechanisms of all kinds and restoration of antiques, which he does absolutely free. This work provides most intricate game for the brain.
The experience that he wanted to share is more in the field of know-hows, methods, gadgets he invented, embellishments, styles and history. As for his specific concepts, Levin’s hallmark mechanisms are different automatic shields (US patent in progress) and guards, variety of different locks and decorative springs and sliding parts.
But here is my answer to the automatic lovers
Every knifemaker knows –the borderline between any folder with the locking mechanism which legal, and an automatic in many states is very thin. The difference is in a piece of steel, wire, brass, plastic, coil spring from pencil, even piece of wood may convert your knife to the auto mode. The question only is in how liberal administration is, and, of course, the interpretation of the laws of this particular state. Whether to put the spring, or not, is up to you and to the rules of the state you are in. In NY it is impossible.
When years ago we had an opportunity to work not only in NY, it was much easier to experiment. Now we live only in NY, and Jack demolished his shop several years ago. Even providing you, guys, with any kind of advice or concept in NY State now may be considered as patronizing. Of course, it is not fair and very unfriendly to the American craftsmanship, which before was one of the best in the world. The automatic knife little by little became history. Whatever it is, but we have to accept it. May be more liberal time for American craftsmans will come.
I hope everyone who e-mailed me will find the answer to his question.
Please forgive me, if I sound pathetic.
Jack’s skills and experience are still around automatic knives of this kind- see my amateur video below This knife “Palash” got “Best Innovative..” in Atlanta in 2007 ( I think). The idea of the guard of this fighting knife - to protect the hand. When the guard is folded and is not on a way any more, it’s not a Palash - it’s a camp knife or can be used for any other purpose.
Please lower you speakers volume- music is scary 
http://www.youtube.com/watch?feature=player_detailpage&v=l5phwVBqRAY#t=27