Here's a link to a scratch awl:

Malco Tools A0 6-1/4" Reg Grip Awl | ToolBarn.com

Iv'e used these since the 60's, great quality, and inexpensive. I have all the different sizes they sell, but love the AO size
for marking metal. All the HVAC shops use the AO, and the shaft is 1/8".
Rich