As it's a new year, let's try another set of things as I skipped November due to a heavy workload.
Wealth creation - it's something alluded to in Covenants, and frequently a focus for player character magi so they can live well beyond the means of an average covenant. So let's create some examples, and think of pitfalls, ways to make it seem less obvious to mundanes, and cost it up.
Day 1 - fake mining
I will look at real mining later, but a fake mine is easy - have a place that looks like it could have ore, but then magic up the finished item.
Base metal in terram - 1 cubic foot is base CrTe 5. As a ritual using vis, the minimum level is 20, so using base 5 + 1 range touch (create a block of metal at touch range) allows 2 magnitudes for size, that is 100 cubic feet. To use metric measures, that is 2700 litres. You can use densities in g/cm cube and that will give you mass in kg/litre. As we are creating 2700 litres a time, you will get 2.7 metric tons x density in g/cm3
Common metals - lead 11.34, iron 7.87, copper 8.93 - this gives
30.6 tonnes of lead
21.2 tonnes of iron
24.1 tonnes of copper
Multiply this by the values in City & Guild and you see you have over 1000 mythic pounds of metal for 4 pawns of vis, with a ritual a CrTe specialist can research the moment they have a lab set up.
Now, the Ore mountains in the Rhine Tribunal have specifically been set aside by the Holy Roman Emperor for people to prospect, and anyone mining lead, iron or silver there can produce it tax free. Across Europe, you can research what metals were mined and produce fake mines and people may not suspect anything.
For real discretion, you will probably need an illusion of the sound and smell of smelting coming from a building so people believe all smelting is occuring where you are directing them to.