I've had many people ask for this template since using it on my stackable parts trays, and this video covers that and a few other things.
More detail on the dovetail plug jig and the free template here:
https://ibuildit.ca/projects/the-dovetail-plug-template/
Stackable trays video where I use the plugs: http://youtu.be/KFuPSFUR3zY