Most extant stays I have read about are finished pattern piece by pattern piece and then whipstitched together. However, there is an Swedish example in Brita Hammar and Pernilla Rasmussen's Underkläder that have been put togther with the right sides of the pattern pieces put together and then stitched like that. It is noted that these stays probably wasn't made by a staymaker, but as I'm not a staymaker, I don't feel bad that I make them like that. I started with sewing the front and back together, putting the right side of the bottom layer of linen to the right side of the silk (which has been basted together with the second layer of linen previously).
I then pressed the seams, folded so the right sides are, well, right, pressed again and then basted the three layers together.
Then I sew all the pieces togther, pressed the seams and stitched them down. It should be noted though that I have never seen stays being made that way so I don't claim any historical acuracy here, but it works for me.
The boning channels were next. My original plan was to make the stays fully boned, but after looking through Underwear: Fashion in Detail I fell for the green stays on page 122, which has pretty cross-stitched decorations. I'm not copying the boning pattern, or the decorations slavishly, but I'm using that for inspiration. The boning channels are sewn with white linen thread that I inherited from my grandmother- she used it in lace-making. I like it, because the stitches shows up better than with ordinary thread. The boning channels are 1 centimetre wide and the channels for the decorations either 5 or 8 milimetres wide.
The lacing holes are sewn with the same linen thread, vaxed. One of these day I'm going to becoming great at sewing them, but that day isn't here yet...
Another alteration to my original plan was the decision of binding the stays with chamois leather. A little digging brought me a supplier in Sweden and it took me two days to get it. It's very soft and supple and has a pale yellow colour. To rest my hands a little a took a pause in making the lacing holes and cut out strips of the leather and bound the stomacher. I can tell you that with a sturdy needle it was no problem at all to sew on a machine. The leather is quite stretchy and it was very easy to sew the point of the stomacher. I wouldn't sew the binding of a pair of tabbed stays a machine, but I will on this pair.
Folded over and stitched to the backside. The binding is 5 milimetres wide and much more padded than a fabric binding. Not a bad thing when it comes to stays.
My next step will be to cut out the shoulder straps and attach them. Then decorate the stays, my plan is to use white and pale yellow silk for the cross-stitch. Boning, binding and then put in the lining. It's a fun project and I look forward to try them on.