I think I spent a total of about $4.00 for more than enough material to build these little chisels.
That was the cost of one 3/8 inch wooden dowel, a piece of 1/16 diameter music wire and a piece of 5/64 dia music wire.
The music wire is available at places like Ace Hardware or a local hobby shop. Those who build flying model airplanes use this stuff for all kinds of things like landing gear, push rods etc. I mention this because that's the reason hobby shops carry it.
The wire is pre hardened so cutting it is a chore unless you anneal it or use a grinder.
It also helps to anneal it so you can pound the end out flat to make the blade of the chisel. Then file it to width, and file the 20 degree angle on it.
Reharden it using a propane torch and oil for a quenching fluid. Gently temper it to a straw yellow color (450 degrees F).
Grind and hone the cutting edge on it, then polish it to a mirror finish.
Drill a hole in a little piece of wooden dowel and insert the chisel.
I usually file a flat on the handle on the straight (untapered) side of the chisel so I have a easily seen indicator to let me know which way it is being held. These old eyes don't see the chamfer on something that's only (1/16 inch wide.)