I started with this pair as I was waiting for both the synthetic whalebone and the JP Ryan stays pattern to arrive in the mail.  This pattern only has 5 pieces total – one front, two sides, two backs.  For 18th century stays that is very minimal.  Only 4 seams!  I decided to leave the seam allowances in and bone each piece before sewing together by machine.  Here is the front with boning channels drawn in, similar to the picture on the pattern envelope:

Front with boning channels drawn in – ready for (annoying) sewing stint.

I have not done horizontal boning channels this way before but I read about it on other blogs, and it worked very well for me.  Instead of adding the horizontal bones in a third layer of fabric, you just don’t sew over the little square areas where the bones overlap.  Then you can insert both the vertical and horizontal bones between the two pieces of fabric.  It does make for a lot of starting and stopping though.  Here is the front with the boning channels sewn.  See all of the loose thread ends from stopping and starting?

Front with boning channels sewn and bones inserted.

No worries – those threads will be hidden by the silk cover, which gets basted on right before assembly.

Now for the sides.  It is very important to make sure there is at least one bone extending into each tab:

The back has to be done in a different sequence since the center back seam on each side is sewn and turned.  I sandwiched the silk cover between the 2 canvas pieces and seamed them together, turned, and pressed with the silk cover on the outside.  The two center back boning channels with the lacing eyelets between will be sewn through the cover fabric as well.  I flipped the cover up to so the one channel next to the side back seam though.

Backs – inside out to show the side back boning channel.

At this point I basted the silk cover pieces to the sides and front, and then seamed them all together.  I did a quick try on and they do fit!  However I didn’t reinforce the seams before I tried it on, and one seam started to rip, so I didn’t get any pictures.  I will not try them on again until I finish binding them.  But here are the stays assembled with the top binding of petersham ribbon applied:

Late 18th Century Stays – front and back

Note: the metal eyelets are NOT period correct.  To be 100% accurate it should have hand bound eyelets.  I decided to use them in this case, since I do not expect to ever wear these stays without a gown or jacket over them.