I'm sure most production flat wrenches are punched out of a piece of
sheet, and deburred.

I need to make a couple flat wrenches for some collet chuck tool
holders, but I neither have such a huge press, a desire to make a punch
and die for one of each tool, nor stock on hand of suitable thickness.
What I have handy is 1" thick flat bar. I was thinking I might cut my
wrenches into the top surface of the flat bar, slice them off with the
bandsaw, and then grind them roughly flat with a bench top belt sander.