Jean Stark mentions a special tool, "grooved 1-1/2" pliers (groove
must accommodate 14-gauge wire)" on page 59 of Classical
Loop-in-Loop Chains. It's used to shape 14-ga wire around a small
dowel so it forms a keyhole. The wire is so thick that it's hard to
shape using regular pliers.
I didn't see a picture of these pliers and couldn't find them in the
Rio Grande catalog. Is this something you make yourself?