After looking at lots and lots and lots of pictures I’ve finally started on this project. The first piece I’m making for him is the undershirt. I’m making a neckline as is seen in this woodcut.

I cut out two panels of linen 60″x60″. At the center of one I cut the front neck slit. I then sewed these together at the shoulders. That is at the top-right and top-left of the fabric I flatfelled the outer 10 inches* (leaving ~40″ at the neck opening). Then I went around and cartridge pleated the neck. I did three strands of thread and will cover this inside and out with bands that are about 1″ wide (it’s about 1/2″ from the selvedge edge of the fabric and the first strand.. then it’s about 3/4 inch from the top strand to the bottom strand). This leaves a nice finished ruffled edge (selvege) at the neckline.
* it’s about 9″ from his neck to the point of his shoulder. 9″ plus ~1″ for seam allowance.