Wayne Parham Messages: 18835 Registered: January 2001
Illuminati (33rd Degree)
There's a link to a converter program that will help you convert inches to millimeters on the π Speakers website. Scroll down to the bottom of any page and you'll see the link.
Accuracy to the nearest available millimeter is all that's required. You can use 19mm wood stock in place of 3/4", for example. Even 18mm is fine.