Not cheap, but here's what the 'pros' use:
http://www.aircraftspruce.com/...R+CAN+CUTTER&x=0&y=0
PANTERA INTERNATIONAL
A DE TOMASO CAR CLUB
Presents the De Tomaso Forums
The On-Line Meeting Place for De Tomaso Owners and Enthusiasts From Around the World
Clicking on the banner will take you to the sponsor's website.