Thanks for the feedback! I will try to think about how we can make it more intuitive. To make iron, build a smelter, then use iron ore and coal that you have mined to create Iron. (You can see what the machines make in the Craft menu [hotkey C] , and then the recipe for each built machine is shown in the Process menu [hotkey P].) The help menu also has all recipes and what the machines produce listed under the Materials subheading.
