Custom Gravity knife anyone tried making one?

[Robert Hankins]

Custom Gravity knife anyone tried making one?
Have been trying to get a workable design that doesn't look like the WWll version...Still having trouble with the locking mechanism.
Bruce Evans being the creative wizz that he is has offered some good ideas, just having trouble making it work.

Love the idea of a fairly quite knife that slides out of nowhere
Want it to have a 4" or so blade with a tight lockup...ANY ideas would be helpfull at this point so nothing is off limits!

 

[Lucky Bob]

Gravity knife, or a "paratrooper" knife?

From what I understand, the first is simply a single-action OTF without a spring, and the other is actually fairly slow to open (there's a name for that type of parallelogram mechanism, but I'm blanking on it.)

This is what I've always seen called a paratrooper knife: http://www.gungfu.com/pics_info_pages/knives_tactical_paratrooper.jpg

And this is a grav knife: http://www.admiralsawesomeknives.com/images/silvergravitylg.jpg