This project of slipcovering the sofa-bed has turned out considerably more complicated than I anticipated, mainly because I knew nothing of the rigid hardware built inside the thing. The serious commercial upholsterer who put on the burnt-orange corduroy in the 1970s took the piece completely apart, but I don't have the equipment or the space or the experience to do that. So I must invent workarounds like the odd-shaped pieces above to give the illusion of upholstery once everything is back together and the innards are hidden.
All this time I had been postponing the day when I would have to deal with the odd-shaped trapezoids that constitute the side-pieces of the backrest. Today was the day I had been postponing. So I figured out an approach (via about 20 tentative sketches) and then gradually got on with it. I use the black-headed tacks when they will be covered by another layer later, but I use the smal brass "escutcheon pins" when they will remain visible.
As luck would have it, both yesterday and today I had window restorers inside the San Francisco apartment of my daughter and son-in-law, these genial window restorers introduced and urged upon me by the building maintenance guy. They took the windows off their hinges and planed and sanded them, replaced the hardware, rehung and repainted the windows, also scraping and repainting the wide (formerly grimy) ledges surrounding the windows on the outside. Very nice guys, skilled workers, but I felt like thrust into this uncomfortable responsibility for something I knew nothing about. They wished me a Happy Thanksgiving when the left today.