I ended up making all 13 drawboxes, however one or two were a bit tight, I cut all the ply with stops on so they were identical in dimension, it was just that the divider on the narrow drawers was 1mm off centre. Next time I will leave more tolerance on the draw boxes. This meant that I had to shave a bit off the drawers. Just over 1mm was needed so I took just over half a mill of each side with the rabett plane I was given a few weeks ago.
Nice shavings
I then spotted two issues, first I put the small drawers in slightly out of square. I used spacers to do it so at first I was scratching my head until I looked at the spacers. They were supposed to be the same but for some reason one as been sanded down. I use the plastic spacers you can buy from screwfix in 1, 3, 5, 8 and 10mm etc. I will sort this tomorrow, should only take a few moments. It didn't explain the reason the drawers were tight as they were tried before using the spacers. I seem to be making a bit of a meal of this!
The next issue was that the drawer spacing on each side would have been different as there is a horizontal divider on the right, but not the left as on the right there are different drawer widths and the vertical divider has to rest on something.
So I decided to put in a divider on the left to even it up. As the cabinet was built I couldn't use dominoes, biscuits etc. so blew the dust off a cheap pocket hole jig I bought many years ago but have never used. It was a bit wobbly using the built in clamp alone so I added a couple of additional clamps. The machining of the jig was a bit wonky and as long as sawdust there was a fair bit of alloy to begin with but did the job.
So now installed so the height of the drawer fronts on either side can be the same.
I'm now cutting the veneer and ply for the drawer fronts.
Cheers
Andy