Well, I have a little stash of off-the-shelf shoulder pads for sewing, but I am being anally retentive about authenticity here and really knit the pads for the Briar Rose. And this is how:
I knit a square (about 5″ x 5″) in garter stitch
I cut three triangles of decreasing size from padding material
I made a “sandwich”
I folded over the square diagonally. Step 5 (no pic): I closed the seams with a row of double crochets (the British ones ).