Customers will now appear and request a custom made weapon if you have no undiscovered locations visible on the map. They pay well, but they are VERY specific, and won't pay unless you get it right.
Customers will now also spawn more frequently, but maintain the cap of 3 at any one time.
There is now a board beside the smelter, on the ore stand, that records the recipes for any alloys you've discovered. If you discover them by trial and error, you must actually smelt something for the recipe to appear. If you successfully make a custom weapon, the customer will pass on a recipe they've heard elsewhere.
Grabbing red hot metal in your hands instead of using the tongs is now a reeeaaaalllly bad idea....