A few easy things that would make our lives a lot better:
1. Molds for metal items should show how much metal is needed. It feels very weird not knowing how much metal is needed for a frying pan or a shovel.
2. Anvil should only unlock after discovering hard metal. Again, most people probably built the mold for it, just to find out you can't make it with any of the metal you discovered on level 1.
3. Molds should inform you they need to be built next to a furnace to work. People build molds out of the way, and then figure out they can't pour metal in it because it's too far from the forge.
4. Recipes of items requiring Anvil / Smith's hammer should unlock only after discovering the Smith's hammer. Just like discovering the frying pan unlocks recipes that require it. It's very sad to see new recipes you unlocked, just to notice you won't be able to craft them because you don't have an anvil and hammer (and can't make it for a while). Eg. metal buttons or glass blowing rods.
5. As suggested in the comment: Allow to inspect the mold to know how long it's going to take
These are all small things, but would make it better especially for people who are new to the system (thinking ahead)