Good morning.
I give you an idea and you can throw it away. But I like it: "Cement".
Create a new material with which to improve the quality of certain objects, aesthetic improvements of the terrain and more.
Step 1. Obtain stone (any type or specific to the developer's taste).
Step 2. grind it either with the quern, milling machine or a cool new stone crushing device that could work with the windmill. (You get from here two materials "Gravel" and "stone flour") The gravel can be used for paving. It would have the same colors as rock paving but with the pattern of very small stones as dots. The quality obtained would be the same as the rock used.
Step 3º Bake the stone flour with fuel in a Kiln. or a smelter for a long time. I would put a little less than tarkiln but similar. The quality of the resulting cement is calculated by using the quality of the 3
Step 4 Use of cement: Creation of cement paste by mixing cement + water. or concrete by mixing gravel+cement+water. Where, obviously the qualities are weighted.
With cement you could create new buildings with bricks or add it to the creation of some Furnaces to improve qualities (like spices in food).
With concrete you could implement wooden molds with which to make Garden pot, treeplanter's pot, bricks. etc. (the wood would influence the final quality.
More stuff: Curiosities, tools, fertilizers....
what do you think?