I've made most of the undershirt to connect the sleeves to. That's made out of leather too. I bought silky solid fabric for the frilly cuffs on the sleeves. I'm not sure what to use for the frills in the collar yet. I saw some fabric in Jo-Anne Fabrics' wedding section that looked exactly like as the frills in this picture:
However, I really like how they look in this picture, though I'm not sure what kind of material was used. Wool maybe? What do you think it's made of?
As for an update on the project, I've run out of sheepskin for the hood and most of the rest of the outfit. It took up a lot more hides than I thought it would. I plan on getting more leather as soon as I can, but I don't want to splurge on that yet as I'm planning on getting the pauldron made for me before that.
In the mean time, I'm going to make the inner hood out deerskin leather. Next, I'll use my sheepskin scraps to make as much of the jerkin as I can.