Barry, I've made boxes with dividers and used an EW jig to make the dados. What about that process doesn't work for you? I use a guide bushing and cut the fitting edge of the jig with the dado bit. 1/4" ish stock is no problem with a 1/8" bit. It does take a little getting used to working at that scale. You need to be aware of which edge you need to align with to ensure the dados are exactly placed. And, of course, a light touch is needed but given the boxes you've pictured, you are clearly there.
Last edited by PhilBa; 03-07-2020 at 11:19 AM.