Hey Warren,
I just got one of these
Xikar mutitools from Bao.
It fits great on my keychain and it's very durable, handy, and works great.
I had a whole pile of punch cutters and I just gave them away. I think I sent them all to Chas.
They really incredibly suck. Seriously. They're heavy in the pocket and clunky, too.
I think you'd very much enjoy the multitool if you want a keychain cutter.
They look incredibly huge, but they fold up smaller than a pack of matches.