Gambeson
This is my old primary under-mail gambeson, and it was machine-sewn. My current gambeson developed from this one and was hand-sewn throughout.
For this gambeson, the padding was reduced slightly at the arms to allow more flexibility, and unlike the drawn gambeson on the previous page this one has a short slit at the front to allow more leg movement. It's not obvious in this picture, but this gambeson also has thumb straps stitched into the sleeve ends and back of the neck: this helps prevent the sleeves riding up the arms as the mail is put on, and the neck loop helps pull off the garment.
My new gambeson is made from a light brown, pure linen, and was hand-stitched using wool and linen threads. Linen threads were used for the cloth, hems and joints, the wool for the quilting. It was a slow process - I took about half an hour per quilt run - but I got a much better "quilting control" during manufacture than I ever could with the sewing machine. The new gambeson is slightly longer than this one, to go with my new, full-length hauberk, and it has an undagged lower edge, along with a tightish integral collar with a lacing up the side of the neck. The collar provides protection for my neck under the hauberk, and it doesn't interfere with my use of a heaume. It's also good at keeping the sweat off my mail, though I am finding my hauberk rusting at the neck and wrists.
I'm still looking into the mysterious "espaliers" mentioned in period documents - are these proto-coats-of-plates worn over mail, or defences/padding worn under mail?