My previous every day knife was a Kershaw 1670TBLKST with SpeedsafeTM spring assist. I love having spring assist, unfortunately the blade was less than high quality, the tip bent and broke while folded in my pocket. So I used the same high carbon mystery steel from before to make myself a new blade.*
I started by covering the original blade with masking tape and outlining the space available inside the handle.
Then I drew the new blade shape on the tape, cut off the remainder, and traced it onto the steel and cut it out.
Next I had to make the new blade work with the old handle, this meant grinding and hand filing the two to be identical.
One problem I was having was in locating the detent on the new blade. I didn't want to drill through the hardened steel to transfer the mark through, and I don't have any precision measuring tools to aid me.
After some contemplation, I noticed that the detent had worn a line into the paint of the blade, and after repeatedly testing the swing of the new blade a similar line had been left on it. So I simply punched a deep divot at the end of that line and it seems to work perfectly.
You can see that I changed the blade length and profile, and added a flapper to help open it with a thumb-stud.
My grind is nowhere near as good as the original unfortunately, but once I get better I can make redo it or make another one. That's the beauty of having these kinds of skills: you're never stuck with something inferior if you're always improving your craft.
*Kershaw's warranty position is that if your blade breaks, you broke it, and it is not covered by warranty. They will replace and sharpen blades with new stock for a fee of $10. For them to be able to cover the blade and labor for only $10 there's nothing telling me that I'll get any better product than I had before, and another chipped blade will be only a matter of time.