Before I started this I did not know what a gambeson was supposed to be.
Turns out that it is a sort of padded tunic used in medieval times uder a coat of mail for protection.
It is also used now-a-days by SCA (Society for Creative Anachronism) people
I researched a bit and decided to make 2 tunics and sandwich them with synthetic padding. We went for synthetic for ease of washing and because it is lighter in weight.
The main material is upholstery twill linen.
I made a toile and then I made the 2 layers of linen tunic. This was simple enough but the quilting of the many layers was a bit of a nightmare.
If I ever wanted to make a second one I would make and quilt the separate parts and then stitch them by hand.
These are details of the gambeson-in-progress.
The tunic was made in one piece opened from the wrist to the bottom of the skirt on both sides. These were then stitched by hand using two passes of whip stitch. I have created a series of crosses by reversing the direction of the stitch for the second pass on the same seam.
This is my take on Aragonrn's grey shirt. He is wearing it in "The company of the ring" and, luckily for me, it is mentioned in the extra material of the Lord of the Rings box set I received for Christmas years ago. 
I started using a commercial pattern: Butterick 4486. I then proceeded to change it almost completely. I have added a yoke. The white toile has a too-small-yoke that I then enlarged. 
I have replaced the cuffs with draw strings and I have divided the sleeves in to pieces. The top part was replaced by a smocked section. The drawstrings and the neck closures are cords made on the lucet.
