My continuous run of days in the workshop got interrupted, but I have managed to move on with a few bits and pieces, so here's a not-quite-final update.
When I left off I was thinking about the back and decided on the reclaimed matchboarding, plus a little bit extra.
This has now all been sanded to clean it up and had a coat of sanding sealer shellac applied to the front, then a coat of water based polyurethane on both faces. That all looks like this:
Also getting a first coat of finish are the toe board, the base and the rails to go across the top.
The new bit of matchboarding got an extra layer of shellac so it's not quite so pale as it was.
It's a big advantage, even in this hot weather, to be using finishes that dry so quickly - with that lot filling up the bench I don't want an enforced 24 hour wait. Also, they are both really easy to apply and brush out even.
To hold the shelves in place, I decided to use some reclaimed metal library strip. When I built a little ash bookcase, decades ago, I used the prettier flat sort, which needs a wide shallow groove behind it, with a deeper groove in the middle where the tabs protrude. This stuff should be easier, as it just screws on. Now that the insides of the uprights had been finished, I set to on those, using the workmate while the bench was full.
This was easy but took quite a long time. I lined the pieces up just above the base and used a couple of small combination squares to measure the same distance in from the edges. Then each hole got poked with an awl, and a little screw was put in.
With tiny screws in softwood, the holes don't need drilling. I used this little Horace Britton tool handle, patented November 28, 1893. The metal cone screws down onto a split shaft, which holds any of a collection of little tools stored inside. Neat and effective, but I think the four-sided awl is the only one I've actually used...
Anyway, this all took a while, as there are nine holes in each strip.
There's another downside to using this sort of surface-mounted strip, that if I cut the shelves square, to fit between them, there would be gaps of about 3mm at each end. I decided I didn't like that, so spent several hours fiddling about cutting little notches on the ends of the shelves.
First, I had a dummy run on an offcut, to confirm the dimensions. I then used this offcut to line up the saw when notching the six shelf ends.
I knifed a baseline and pared all the wood out with a chisel, as if I was doing shallow dovetails. It was a bit of a reminder that redwood isn't always easy to work with, because of the very hard layers alternating with the much softer ones.
I managed to make them all to a standard I thought was good enough for something not actually visible. Tool spotters have probably seen this perfectly commonplace half inch bevel edge chisel before, but it's the one I choose first for a job like this. It's a proper bevel edge, with very fine lands, even if the shaping around the tang and the bolster is pretty crude.
(That rather poor mark says F. WOODCOCK SHEFFIELD, which puts it between 1922 and 1957. When the company was wound up so the directors could retire, their stock of forgings was bought at auction by Ashley Iles - which helped him get started in business. A 10-ton lorry full, for £40!)
I found I got best results by making a sloping surface with the first cuts, so I could then pare horizontally, moving down the slope in tiny steps, from one side, then the other. The last slice reveals the shiny knife cut. I didn't photograph all of this, as I'm sure it's familiar stuff, but here's a half-way shot and a finished notch.
With all twelve notches cut, I could test fit the shelves into place.
They fitted ok, just resting on the metal strips while the unit is still horizontal.
There's still quite a bit of sanding and finishing to do, and the back to fix on. I need to do everything in the right order so I don't spoil the finished surfaces.
Very good wip and good to reclaim materials. 
- Rob