Courtesy of Charlie Rodgers .. in Office 2007/2010 version of Excel format (.xslx).

Check out this offering from Charlie Rodgers .. nice writeup and some great accompanying photos!

Trebuchet plans in AutoCAD and Edrawings. Based on plans from Dec. 1997 American Woodworker article.

The Begginings of a Stanley #4 in Solidworks 2007. There is also an Edrawings model (viewable by anyone with edrawings, a free download for solidworks.com). Still need sht efrog and associated screws, along with the lever cap, but it is a start.