Here is fine Kelley , thanks for the post. You can see that the knife is deep in the Kydex , I have a small spacer I put on the blade when I form it and it presses it deeper into it. That helps it to stay put. The Rare earth magnets I use are 3/4" dia X 1/8" thick , and have 9.7 lbs of "pull force" each. I used 3 on this knife. ( that 9.7 lbs pull rate is in a magnet directly to steel application , here we have .080 of Kydex between the steel and the magnet, so its a bit less ) SO
With the knife set deep in the kydex and the magnets holding it in there , it aint gona fall out. I actually took this one and held it by the sheath and tried to fling the knife out.....no dice , held like a rock , BUT if you just give it a bit of an upward twist on it , when its around your neck , it comes right out, AND you can put it back in with just one hand , just get it close and it "snaps" right in.
I started doing this about 5 years ago , and have made a bunch of them to date.
Hope I answered all of your questions , if not , post up
Dwane