The paneling hides all the ply wood I used and is designed to match as much as possible the existing stairs.
I've been working on this stage for a while now. It took me ages to finally order the timber, I order all I needed for shelves that are going in the landing area and for the sliding sash windows I'll be making next. I cut the timber to approximate size and left it stacked up on the landing for a couple months to season and acclimatise.
Hopefully nothing will shrink and show up. I've allowed for movement of the wide boards and the panels.

One part that did stump me for a while was how to make the panels thin enough. I ended up sawing by hand 250mm wide boards and finished them with a belt sander. It would have been easier if my thicknesser took more than 200mm. With some time end effort they came out OK at about 6mm and flat enough on the visible side.

If I'd had worked out how much moulding I needed to finish of the paneling I would have invested in a bit for the router. At around £7 for 2.4m from Wickes its extortionate.