Also we aren't talking about making tools (a recyclable item and can therefore easily become a saturated market) but consumables like blades and chisels. By making items that are produced in large quantities and used in great quantities and will always be in demand we can be assured sales and therefore profit.
I also suggest we corner the bronze market. A reason to corner something like bronze is because even though higher tier resources need a better consumable a player who can make those higher tier items should have access to workshops that provide greater bonuses than the public ones. In fact I'm waiting to do a lot of masonry work until I can set up a workshop with a really good machine so I can save money on concrete.
Still not a bad idea to move to iron once we have enough people who can work in it. That is IF we are going to corner metal working. That isn't the greatest concentration of our players, we just have a lot of people who've trained into it because they needed consumables. Could instead corner ampule production (would employ at least 3 different professions) or carpentry or masonry construction material (we're not the only ones interested in making a guild, and those others will be looking for hundreds of walls, foundations, roofs, towers, fortifications ect. (Would employ stone, wood, metal, and science at least)).
Could even figure out some kind of set of resources we could corner together as well.