|Intro: I have read many home sewing books over the years on sleeve heads. They all give the same instructions, where you cut a retangular piece of fabric (usually lambswool, fleece, tie-rite, etc.) and either attach it when easing in the sleeve or hand sew it in afterwards. While I don't dispute this method and use it myself on hard to ease fabrics, I do prefer to make my own shaped sleeve heads when sewing with natural fibre fabrics. I find it gives more satisfactory results and supports the sleeve cap better.
Shaped Sleeve Head: To make my sleeve heads I use either Armo Fleece or HTC Fleece (both readily available at Spotlight in Australia). Using the sleeve pattern, I cut a shaped sleeve head approx. 2" wide, and as long as I require. After attaching the sleeve, I hand sew the sleeve head to the seam allowance along the stitching line.
It is possible to buy pre-cut shaped sleeve heads (called Boomerangs by Fashion Fuse in Australia) but I find they are too long/big and better suited to men's jackets. Therefore I like to make my own.