" In the olden days"........when department store work was very common, and the process was "vanila for everybody", no risk outside " normal " was attempted or desired in any way, channel chairs were commonly done. The way they turned out was accepted, the channels were accomodated, and the wood left exposed. They were cut open, on the whole chair most often, face out.
Cottons were used almost exclusively in those days, and they were mid heavy weight, starchy, and at the least patterned and maybe even textured as well.
I was in my late teens at the time, I saw them leave the shop in a brown wrapper, I never saw them personally on the cahirs untill I started to cut them myself. I was happy with my own, but this will still the eighties when cotton ( great disguise cotton )was the norm.
With the popularity of luxury fabrics you do need to invent a whole new plan. I won't, I am sticking to cotton. ( I hope )
Well, for the most part. I am stuck now with upholstery weight crap to put on button tufted barrel chairs with no loose cushion. It's a receding color and has too few threads for safety. Dede, we make it up as we go along, cross your fingers, amd hope for the best.