How about some kind of "tool" item, representing all the tongs, chisels, hammers and files usually found in workshops. Can be imported from the mountainhomes with relative ease or made yourself, if your dwarves are skilled enough. Also make decent trade goods.
Each and every workshop would have a menu where you could designate the amount of tools present in the shop. You could do this at any time, so you if you really liked micromanaging, you could take just a few of them and have the dwarves haul them to whichever workshop you are using at the moment. The number and quality of tools in a workshop give hefty skill bonuses and penalties to dwarves using the workshop. They could also be needed at kitchens and fisheries and the like, representing knives and cheese graters.
This would be abstract enough to avoid excessive micromanaging, while still portraying the simple tools -> complex tools progression. A metalcrafter can make tools, which he can use to make -tools-, which he can use to make +tools+, and so on. Unless you get a fey metalcrafter, you will have to do this for quite a long time to get sufficient metalcrafting skill to get higher on the tool ladder. I think a mediocre no-title skill, the kind you sometimes get from immigrants, should be sufficient to make serviceable tools that allow you to manufacture anything, if at a penalty to quality.
If you don't want to bother, you can import them. They're abundant back at the Mountainhomes, so they would be reasonably cheap to buy. They could be further sold with profit to the elves and humans, who have a greater need for the things because of their less developed industry. Just like Sid Meier's Colonization.
As an added bonus, this method would also be unnecessarily complicated, especially if we have wooden or rock tools for the very early stages of civilization. It is the dwarven way!