Last September I finally plucked up the courage to make myself some C18th pocket hoops so that I could start doing some 1750s/1760s reenactment if and when required. They only took a day - or a few period drama DVDs!
To get the measurements I stood in front of my mirror with a tape measure and played about to get the size I wanted. Excluding the boning channels, there are 3 pattern pieces to the pockets - the back, the front, and the bottom.
Measurements (excluding seam allowance)
Back: 10" long x 9" wide.
Front: 19" long x 18" wide.
Bottom (a 'D' shape): 9" along the straight x 18" on the curve.
I used a striped heavy cotton (ticking) fabric as the hoops will be under a lot of pressure throughout use. First I started by turning over the edges (apart from the top of the front piece) of all the pieces twice and machine sewing them so that they were neatened - n.b. the curve was only folded over once. I the folded the top of the front pieces over an inch and folded over again, then stitched, to make a channel for the waistband.
After this, it was time for the boning channels - 3 on each pocket hoop. These were 20" long x 1" wide (the width of the boning plus seam allowance). I used the sewing machine to stitch them to the front pieces, starting and finishing about an 1.5" from the edges. The first one was stitched 7" from the top (not taking into account of seam allowance here), the third at the bottom, and the middle place half way between.
I then hand sewed, with double thread, the back pieces to the fronts along the sides - the back pieces start at the bottom of the front pieces and finish roughly in line with the boning. The bottom pieces then followed - these needed a little easing as I sewed, but weren't too hard.
Once this was done, it was time to insert the boning into the channels. I had some steel boning left over from when I made my C16th Spanish farthingale so I used this - it measured about 1/2" wide. I cut six pieces at about 17.5" long (it is recommended that when boning anything, the bones are at least 1/2" shorter than the boning channel), and protected the ends with pieces of masking tape. After inserting them into the channels, I folded under the remaining channel fabric and stitched down.
As for getting your hands in...I cut a slit in the centre of the fabric of each pocket starting about 1/2" from the bottom of the waistband channel and finishing about an inch from the edge of the first boning channel. This was bound with some matching bias binding.
Once I has threaded through some cotton twill tape, the pockets were finished!