A DDR3 button lock knife kit that I built several(like, 9 or 10… wow!) years ago.
I had put the optional spring in it at the time, and made it a switch blade. Fun knife to use, and carry, but the safety tends to shift to ‘off’ in my pocket, and then the knife opens, and I’ve come close to stabbing myself with it. Not to mention switchblades are technically illegal to carry here.
So, I used my bit kit to take it apart and remove the spring, then re-assembled it.
A little fiddling to get the pivot tension right, and now the blade is 99% tight, but all I have to do is push the button and flick my wrist to open it, and the same motion reversed to close! And it works perfectly left handed too! All I need now is to drill and tap a bolster for a pocket clip…(Like THAT will ever happen! I Hate tapping threads..)