The crafting station is in a cave in Northguard. Enter Northguard, and head around to the right towards the far side. You will eventually see a cave across the river and there is a crafting station inside.
Good luck. There are some fine things to craft there. :P
All wintertusk gear must be crafted at the crafting station in Grizzleheim. It is across the river by Mirkholm Keep. You will see stepping stones that lead across the river in front of the door. It's right on the other side of the bridge on the right side.