Here's the two-stroke degree wheel from Alex Whittaker's Engine Lab series that start's this month in RCM&E (Aug 2008 issue)

You can download this 'actual size' disk by right-clicking on the item and then select your download location by choosing 'save target as'.

As Alex suggests, the wheel can be printed out (on paper or better still a bespoke CD label) and stuck onto a CD. Engine Lab Pt.2 will be in the Sept 2008 issue.