Sorry!  Just got back on site.
Process: each handle slightly different.
Started with Disston drawing.modified it. Try using exotic woods. Drilled holes & openings, band saw, scroll saw, file, sand, finish used whatever I had left over opened…. Made  Modifications at each operation.  Not into metal, Use old blades cut to size.  Figured if one of marrow long tails breaks ( hasn’t happened yet) simply file & sand, move on….
Jim