I believe it is the same as the plate on the Incra/JessEm Mast-R-Lift. I made my own template. Easy to do. The first picture shows the various bits I used and the second shows the template itself. Here are the steps I took:
- routed out the through opening using a straight bit with a bushing against the template shown in the second picture. cut was about 3/8" deep.
- used a jig saw to cut out the opening
- used a trim bit with a bearing to clean up the through cut from the other side
- then used a rabbet bit to make the actual plate opening from the top.
You could adapt the template to use a 1/2" pattern bit instead of a straight bit if bushings don't work for you. A pattern bit might make it easier to align the template halves but you will need to make it smaller.
Measure twice, cut once and CROSS OUT THE WRONG MARKS.