I've been having fun for the last few weeks making files into knives. It's a lot of work but it's also fun and satisfying. You can put a price on fun and satisfying. I'm not going to go into the process of making a knife as there are a lot of info on the subject. I'm a beginner so take it for what it is worth, but some of the tips I give are green horn tips:
Files:
I've been searching swap meets for files with brands like Grobet and Nicholson, these apparently are the best ones for this projects...
Forge:
A blow dryer is your best friend, it will heat the coals up to get the knives up to non-magnetic in no time!
Quench!
I saved up oil from my fried chicken for this process, I find it saves me a lot of headaches from the Mrs. as when you temper the blades after re-hardening, your oven does not smell like motor oil.
Handle:
the handle itself is an Art! I went with paracord style as it's simple and I'm just wanting a basic knife.
Notes: in the re-hardening there is a chance your blade will warp, DO NOT bang on it, either un-harden then rework the metal or clamp to a solid piece of steel during tempering process. The longer the blade, the better chance it can warp
Good luck