The diagram below was archived from the CAMS web site, currently at

http://www.montgomeryauto.net/cams/techtool.html

I kept this for personal reference, as the above URL keeps changing.

And this is how my tool looked.

Another idea with the same theme is shown in this tool, made by WCMC member Tim Martin for the 1.8 motor. This is a long bar of angle iron, with two holes and an arc ground into the face. I borrowed it for use on a 1.8 liter miata.