I was planning to use an undersized plywood bit to cut the dado’s for the drawer dividers – and since I mixed cabinet grade and regular plywood, I would use a full size bit for the parts that were out of full 3/4″ thick. I fretted about this for a couple days… and as I was getting things set up it hit me. Why not just mark out the widths, and use a template bit with a straight edge bit to make the cuts?
It’s a bit hard to see in the 2nd picture, but I’ve used 3 boards here – the router is sitting on the template (straight edge). To the left are two boards that are clamped in place to ensure the template piece doesn’t shift, because I can’t clamp the template without interfering with the router.
It’s not a perfect fit, so I tuned it up with a dado side plane – it just took 3-4 passes to set the boards into place. All in all, it took less than an hour to complete fitting the parts together. They are fitted well enough to work.