The study parts in this course are documented with either metric / SI or British Imperial / US Customary system dimensions. Each system of measurement is used for approximately half of the parts.

The metric system parts are primarily dimensioned using millimeters, but a few use meters.

The British Imperial / US Customary system parts are dimensioned using inches.

If you prefer to work on parts using a particular system of measurement, there are separate sections dimensioned in inches and millimeters. The inches section comes first. If you prefer to work in millimeters, jump ahead to a later section.

I personally encourage you to practice modeling parts in both units of measurement. Although you may primarily work in one system of measurement, being familiar with the other is always a good idea.

British Imperial / US Customary System (inches)

These parts begin with ATP-001

Metric System / SI (millimeters)

These parts begin with ATP-1001