Wow, is there no end to forum threads on here that don't interest me, they never end!
I have never built a custom knife but owned and have used a few. Two that stand out were built by my old man and a buddy of his in the mid 60's. One was built from an industrial power hacksaw blade, the other from a planer mill blade. The power hacksaw blade being the thinner of the two was the filleting/steak slicer knife, the much heavier plainer blade was the "butchering" knife. My old man, being a sharp edge fanatic whenever a knife was involved, never failed a warning when someone picked up one of his knives at a community butchering day "be god damn careful with that thing , it's not fussy what it cuts". When an animal hit the ground there was no need for a saw when that big knife was there, I have opened beef & moose briskets & H-bones with one easy pull.
I think the point here that might interest everybody is the fact they didn't have a forge as we know them for the "build"...just an ordinary acet. torch and a pail of cement powder to turn the steel from intensely hard to a softer state for the shaping work and back to hard (with five gallon pail cold water instead of the cement) and then to draw it down just a bit. After the softening stage just an ordinary bench grinder then an angle grinder did the shaping with a little elbow grease and a file to finish. first sharpening after drawing down was done with a soft wheel on the same angle grinder followed by numerous stretches' of labor with a emory cloth block to finish.
My old man is long gone but those knives still stick to the magnetic holder beside my mothers counter top...I sharpen them once a year for her....proof that a "Forged In Fire" (love that show) shop set-up would be nice to have but not needed if you have the bare essentials...good steel and a heat source.